PERFORMANCE OF A
TEST
MALIK ALQUB MD. PHD.
Sensitivity of a test
• Ability of a test to identify correctly affected individuals
• proportion of people testing positive
among affected individuals
True patients
(gold standard)
Test
+
－
True positive (TP)
False negative (FN)
Sensitivity (Se) = TP / ( TP + FN )
Sensitivity of a PCR
for congenital toxoplasmosis
Patients with
toxoplasmosis
Rapid test
True positive
54
False negative
4
58
Sensitivity = 54 / 58 = 0.931= 93.1 %
Specificity of a test
•
Ability of test to identify correctly non-affected individuals
- proportion of people testing negative
among non-affected individuals
Non-affected people
Test
+
－
False positive (FP)
True negative (TN)
Specificity (Sp) = TN / ( TN + FP )
Specificity of a PCR
for congenital toxoplasmosis
Rapid test
False positive
True negative
Individuals
without
toxoplasmosis
11
114
125
Specificity= 114 / 125 =0.912 = 91.2 %
Performance of a test
Disease
+
Yes
No
TP
FP
FN
TN
Test
TP
Se =
TN
Sp =
TP + FN
TN + FP
Distribution of quantitative test results
among affected and non-affected people
(ideal case)
Non affected:
Number of people tested
Threshold for
positive result
TN
0
5
Affected:
TP
10
15
Quantitative result of the test
20
Distribution of quantitative results
among affected and non-affected people
(realistic case)
Non-affected:
Number of people tested
Threshold for
positive result
TN
TP
FN
0
5
Affected:
10
FP
15
Quantitative result of the test
20
Effect of Decreasing the Threshold
Non affected:
Number of people tested
Threshold for
positive result
Affected:
FP
TP
TN
FN
0
5
10
15
Quantitative result of the test
20
Effect of Decreasing the Threshold
Disease
+
Test
Yes
No
TP
FP
FN
TN
TP
Se =
TN
Sp =
TP + FN
TN + FP
Effect of Increasing the Threshold
Number of people tested
Threshold for
positive result
TN
Non-affected:
Affected:
TP
FN
FP
0
5
10
15
Quantitative result of the test
20
Effect of Increasing the Threshold
Disease
+
Yes
No
TP
FP
FN
TN
Test
TP
Se =
Sp =
TP +
FN
TN
TN + FP
Performance of a Test and Threshold
• Sensitivity and specificity vary in opposite directions when
changing the threshold
• The choice of a threshold is a compromise
to best reach the objectives of the test
• consequences of having false positives?
• consequences of having false negatives?
When false diagnosis (FP)
is worse than missed diagnosis (FN)
• Example: Screening for congenital toxoplasmosis
• One should minimise false positives
• Prioritise SPECIFICITY
When missed diagnosis (FN)
is worse than false diagnosis (FP)
• Example: Testing for Helicobacter pylori infection
• One should minimise the false negatives
• Prioritise SENSITIVITY
Which is Preferred: High Sensitivity or
High Specificity?
• If you have a fatal disease with no
treatment (such as for early cases of
AIDS), optimize specificity
• If you are screening to prevent
transmission of a preventable disease
(such as screening for HIV in blood
donors), optimize sensitivity
Predictive Value
• Is determined by Sensitivity, Specificity and the
Prevalence of the disease
• Prevalence is defined as the number of patients per
100,000 population who have the disease at a given time
Positive
predictive
value
(+ PV)
The fraction of people
with positive tests
who actually have
the condition.
Negative
predictive
value
(-PV)
The fraction of people
with negative tests
who actually don't have
the condition.
The sensitivity and specificity are
properties of the test.
The positive and negative predictive values
are properties of both the test and the
population you test.
If you use a test in two populations with
different disease prevalence, the
predictive values will be different.
A screening test is most useful if directed to a
high-risk population (high prevalence
and high predictive value).
How to remember
Sensitivity: "I know my patient has the disease. What is the
chance that the test will show that my patient has it?“
Specificity: "I know my patient doesn't have the disease.
What is the chance that the test will show that my patient
doesn't have it?"
Cont.
+PV: “I just got a positive test result back on my patient.
What is the chance that my patient actually has the
disease?”
-PV: “I just got a negative test result back on my patient.
What is the chance that my patient actually doesn't have
the disease?”
Now to the Math
Test is
positive
Test is
negative
Patient with
the disease
Patient
without the
disease
A
B
True Positive False Positive
C
D
False
Negative
True Negative
you can calculate
Sensitivity = a / (a+c)
Specificity = d / (b+d)
+ PV = a/(a+b)
- PV = d/(c+d)
Knowing the prevalence of the disease in the
population is necessary for these calculations
Understanding Predictive Value
• Prevalence is defined as the number of patients
per 100,000 population who have the disease at
a given time.
• A high +PV indicates a strong chance that a
person with a positive test has the disease
whereas a low +PV is usually found in
populations with low prevalence of the condition
being examined. A high -PV means that a
negative test in effect rules out the disease.
Prevalence of Disease
• 100 people are tested for
disease. 15 people have
the disease; 85 people
are not diseased. So,
prevalence is 15%:
• Prevalence of Disease:
• Tdisease/ Total × 100,
• 15/100 × 100 = 15%
Sensitivity
• Sensitivity is two-thirds, so
the test is able to detect
two-thirds of the people
with disease. The test
misses one-third of the
people who have disease.
• Sensitivity:
• A/(A + C) × 100
• 10/15 × 100 = 67%
specificity
• The test has 53%
specificity. In other words,
45 persons out of 85
persons with negative
results are truly negative
and 40 individuals test
positive for a disease which
they do not have.
• Specificity:
• D/(D + B) × 100
• 45/85 × 100 = 53%
Positive and negative Predictive Value
• Positive Predictive Value:
• A/(A + B) × 100
• 10/50 × 100 = 20%
• Negative Predictive Value:
• D/(D + C) × 100
• 45/50 × 100 = 90%
Increased Prevalence, Same Test
• Prevalence of Disease:
•
•
•
•
•
Tdisease/ Total × 10
30/100 × 100 = 30%
Sensitivity:
A/(A + C) × 100
20/30 × 100 = 67%
Specificity:
D/(D + B) × 100
37/70 × 100 = 53%
Now let's calculate the predictive
values:
Positive Predictive Value:
A/(A + B) × 100
20/53 × 100 = 38%
Negative Predictive Value:
D/(D + C) × 100
37/47 × 100 = 79%
ACID-BASE
HOMEOSTASIS
AND ABG
Dr. MALIK ALQUB
pH
pH is a measure of the acidity or
basicity of an aqueous solution.
The importance of pH control
• Blood pH Must be Kept Close to 7.4
• Hydrogen ion is extremely reactive and effects many molecules
which regulate physiological processes
• Blood pH is set at a slightly alkaline level of 7.4 (pH 7.0 is neutral)
• A small change of pH in either direction is considered serious
• Blood pHs below 6.9 or above 7.9 are usually fatal if they last for
more than a short time
The importance of pH control
• The pH of the ECF remains between 7.35
and 7.45
• If plasma levels fall below 7.35 (acidemia),
acidosis results
• If plasma levels rise above 7.45 (alkalemia),
alkalosis results
• Alteration outside these boundaries affects
all body systems
• Can result in coma, cardiac failure, and
circulatory collapse
Mechanisms to maintain body pH
1. Chemical buffers
Instantaneous physicochemical reactions that limit changes in
[H+]. Their capacity is limited and cannot fully correct pH
abnormalities.
2. Respiratory regulation
The respiratory system can respond to changes in plasma pH by
altering the excretion of CO2. The response is rapid (within
minutes) and the system has a large reserve capacity.
3. Renal regulation
Plasma bicarbonate is controlled via the secretion of H+ as well
as the reabsorption and formation of HCO3, allowing complete
correction of acid–base disorders.
1. Chemical Buffer
• A buffer is a solution which contains a mixture of a
weak acid and its conjugate base (or a weak base and its
conjugate acid). A buffered solution resists drastic
changes in pH by neutralizing any acid or base which is
added to the solution.
Carbonic Acid-Bicarbonate Buffering
System
CO2 + H2O  H2CO3  H+ + HCO3–
Respiratory
regulation
Renal
regulatio
n
2. Respiratory regulation
•A normal by-product of cellular metabolism is carbon
dioxide (CO2). CO2 is carried in the blood to the lungs,
where excess CO2 combines with water (H2O) to form
carbonic acid (H2CO3).
•The blood pH will change according to the level of
carbonic acid present.
•This triggers the lungs to either increase or decrease
the rate and depth of ventilation until the appropriate
amount of CO2 has been re-established.
•Activation of the lungs to compensate for an imbalance
starts to occur within 1 to 3 minutes
3. Renal regulation
•In an effort to maintain the pH of the blood within its normal
range, the kidneys excrete or retain bicarbonate (HCO3)
•As the blood pH decreases, the kidneys will compensate by
retaining HCO3 and as the pH rises, the kidneys excrete
HCO3 through the urine.
•Although the kidneys provide an excellent means of
regulating acid-base balance, the system may take from
hours to days to correct the imbalance.
ARTERIAL BLOOD
GASES
Objectives
1. Describe the physiology involved in the acid/base balance of
the body.
2. Compare the roles of PaO2, pH, PaCO2 and Bicarbonate in
maintaining acid/base balance.
3. Review causes and treatments of Respiratory Acidosis,
Respiratory Alkalosis, Metabolic Acidosis and Metabolic
Alkalosis.
4. Identify normal arterial blood gas values and interpret the
meaning of abnormal values.
5. Interpret the results of various arterial blood gas samples.
6. Identify the relationship between oxygen saturation and PaO2
as it relates to the oxyhemoglobin dissociation curve.
7. Interpret the oxygenation state of a patient using the reported
arterial blood gas PaO2 value.
Getting an arterial blood
gas sample
Arterial Blood Gas
Drawn from artery- radial, brachial,
femoral
It is an invasive procedure.
Caution must be taken with patient on
anticoagulants.
Arterial blood gas analysis is an
essential part of diagnosing and
managing the patient’s oxygenation
status, ventilation failure and acid base
balance.
Blood Gas Report
Acid-Base Information
•pH
•PCO2
•HCO3
Oxygenation Information
•PO2 [oxygen tension]
•SO2 [oxygen saturation]
Detection of acidosis and alkalosis
• Diagnostic blood tests
• Blood pH
• PCO2
• Bicarbonate levels
• Distinguish between respiratory and metabolic
Normal values
• pH Measurement of acidity or alkalinity, based on the
hydrogen (H+) ions present. The normal range is 7.35 to
7.45
• PaCO2 The amount of carbon dioxide dissolved in arterial
blood. The normal range is 35 to 45 mm Hg.
• HCO3The calculated value of the amount of bicarbonate
in the bloodstream. The normal range is 22 to 26 mEq/liter
Steps to an Arterial Blood Gas
Interpretation
• Step One
Assess the pH to determine if the blood is within normal
range, alkalotic or acidotic. If it is above 7.45, the blood is
alkalotic. If it is below 7.35, the blood is acidotic.
Acidosis Vs. alkalosis
• Step Two
If the blood is alkalotic or acidotic, we now need to
determine if it is caused primarily by a respiratory or
metabolic problem. To do this, assess the PaCO2 level.
Remember that with arespiratory problem, as the pH
decreases below 7.35, the PaCO2 should rise. If the pH
rises above 7.45, the PaCO2 should fall. Compare the pH
and the PaCO2 values. If pH and PaCO2 are indeed
moving in opposite directions, then the problem is
primarily respiratory in nature.
• Step Three
Finally, assess the HCO3 value. Recall that with a
metabolic problem, normally as the pH increases, the
HCO3 should also increase. Likewise, as the pH
decreases, so should the HCO3. Compare the two
values. If they are moving in the same direction, then the
problem is primarily metabolic in nature.
Relationships between pH,
PaCO2 and HCO3.
Clinical cases
• pH:
7.35 - 7.45
• PaCO2: 35 to 45 mm Hg.
• HCO3: 22 to 26 mEq/liter
• pH:
7.35 - 7.45
• PaCO2: 35 to 45 mm Hg.
• HCO3: 22 to 26 mEq/liter
Respiratory Acidosis
• Respiratory acidosis is defined as a pH less than 7.35
with a PaCO2 greater than 45 mm Hg.
• Acidosis is caused by an accumulation of CO2 which
combines with water in the body to
• produce carbonic acid, thus, lowering the pH of the blood.
Any condition that results in
• hypoventilation can cause respiratory acidosis.
Causes of hypoventilation
• Central nervous system depression related to head injury
• Central nervous system depression related to medications
•
•
•
•
•
such as narcotics, sedatives, or
anesthesia
Impaired respiratory muscle function related to spinal cord
injury, neuromuscular diseases, or neuromuscular
blocking drugs
Pulmonary disorders such as atelectasis, pneumonia,
pneumothorax, pulmonary edema, or bronchial
obstruction
Massive pulmonary embolus
Hypoventilation due to pain, chest wall injury/deformity, or
abdominal distension
Respiratory Alkalosis
• Respiratory alkalosis is defined as a pH greater than 7.45
with a PaCO2 less than 35 mm Hg.
• Any condition that causes hyperventilation can result in
respiratory alkalosis. These conditions include:
• Psychological responses, such as anxiety or fear
• Pain
• Increased metabolic demands, such as fever, sepsis, pregnancy,
or thyrotoxicosis
• Medications, such as respiratory stimulants.
• Central nervous system lesions
Metabolic Acidosis
• Metabolic acidosis is defined as a bicarbonate level of
less than 22 mEq/L with a pH of less than 7.35. Metabolic
acidosis is caused by either a deficit of base in the
bloodstream or an excess of acids, other than CO2.
Diarrhea and intestinal fistulas may cause decreased
levels of base. Causes of increased acids include:
• Renal failure
• Diabetic ketoacidosis
• Anaerobic metabolism
• Starvation
• Salicylate intoxication
Metabolic Alkalosis
• Metabolic alkalosis is defined as a bicarbonate level
greater than 26 mEq/liter with a pH greater than 7.45.
Either an excess of base or a loss of acid within the body
can cause metabolicalkalosis.
• Excess base occurs from ingestion of antacids, excess use of
bicarbonate.
• Loss of acids can occur secondary to protracted vomiting, gastric
suction,
• hypochloremia, excess administration of diuretics, or high levels of
aldosterone.
Compensation
When a patient develops an acid-base imbalance, the body
attempts to compensate. Remember that the lungs and
the kidneys are the primary buffer response systems in
the body. The body tries to overcome either a respiratory
or metabolic dysfunction in an attempt to return the Ph
into the normal range.
A patient can be uncompensated, partially compensated, or
fully compensated. When an acidbase disorder is either
uncompensated or partially compensated, the pH remains
outside the normal range. In fully compensated states, the
pH has returned to within the normal range, although the
other values may still be abnormal. Be aware that neither
system has the ability to overcompensate.
• In order to look for evidence of partial compensation,
review the following three steps
1. Assess the pH. This step remains the same and
allows us to determine if an acidotic or alkalotic state
exists.
2. Assess the PaCO2. In an uncompensated state, we have
already seen that the pH and PaCO2 move in opposite
directions when indicating that the primary problem is
respiratory. But what if the pH and PaCO2 are moving in the
same direction? That is not what we would expect to see
happen. We would then conclude that the primary problem was
metabolic. In this case, the decreasing PaCO2 indicates that
the lungs, acting as a buffer response, are attempting to correct
the pH back into its normal range by decreasing the PaCO2
(“blowing off the excess CO2”). If evidence of compensation is
present, but the pH has not yet been corrected to within its
normal range, this would be described as a metabolic disorder
with a partial respiratory compensation.
3. Assess the HCO3. In our original uncompensated
examples, the pH and HCO3 move in the same direction,
indicating that the primary problem was metabolic. But
what if our results show the pH and HCO3 moving in
opposite directions? That is not what we would expect to
see. We would conclude that the primary acid-base
disorder is respiratory, and that the kidneys, again acting
as a buffer response system, are compensating by
retaining HCO3, ultimately attempting to return the pH
back towards the normal range.
Fully Compensated States
Partially Compensated States
partially compensated metabolic acidosis
fully compensated
respiratory acidosis
• partially compensated
respiratory acidosis.
• fully compensated
metabolic alkalosis
Oxyhemoglobin Dissociation Curve
• The oxyhemoglobin dissociation curve can be used to
estimate the PaO2 if the oxygen saturation is known. The
illustration demonstrates that if the curve is not shifted , an
oxygen saturation of 88% is equivalent to a PaO2 of
about 60 mm Hg. With a left shift, the same saturation is
equivalent to a much lower PaO2.
• PaO2; 80 to 100 mm Hg.
• SaO2; 95% to 100%.
ANION GAP
MIXED DISORDERS
THE ALVEOLAR–ARTERIAL OXYGEN
TENSION DIFFERENCE
Malik ALQUB MD, Ph,D,
Anion Gap
• Part A shows normal
concentrations of the major
plasma electrolytes. The ‘anion
gap’ is a way of referring to the
ions that don’t usually get
measured in ordinary clinical
practice.
• Part B shows a situation in which
the anion gap has increased at
the expense of the bicarbonate
and chloride. This is typical of
metabolic acidoses in which the
conjugate anion of the fixed acid
is something other than Cl-.
Anion Gap
• Metabolic acidosis is conveniently divided into elevated
and normal anion gap (AG) acidosis. AG is calculated as
• AG = Na+ - (Cl- + HCO3)
• Normal AG is typically 12 ± 4 mEq/L. If AG is calculated
using K+, the normal AG is 16 ± 4 mEq/L. Normal values
for AG may vary among labs, so one should always refer
to local normal values before making clinical decisions
based on the AG.
METABOLIC ACIDOSIS
• METABOLIC ACIDOSIS
↓HCO3- & ↓ pH
• Increased anion gap
• lactic acidosis; ketoacidosis; drug poisonings (e.g., aspirin,
ethylene glycol, methanol)
• Normal anion gap
• diarrhea; some kidney problems (e.g., renal tubular acidosis,
interstitial nephritis)
Mixed acid-base disorder
• Most acid-base disorders result from a single primary
disturbance with the normal physiologic compensatory
response and are called simple acid-base disorders.
• In certain cases, however, particularly in seriously ill patients,
two or more different primary disorders may occur
simultaneously, resulting in a mixed acid-base disorder.
• The net effect of mixed disorders may be additive (eg,
metabolic acidosis and respiratory acidosis) and result in
extreme alteration of pH;
• or they may be opposite (eg, metabolic acidosis and
respiratory alkalosis) and nullify each other’s effects on the pH.
Mixed Acid-base Disorders
Tips to Diagnosing Mixed
Acid-base Disorders
• TIP 1. Do not interpret any blood gas data for acid-base
diagnosis without closely examining the serum
electrolytes: Na+, K+, Cl-, and HCO3.
Single acid-base disorders do not lead to normal blood pH.
Although pH can end up in the normal range (7.35 - 7.45) with
a single mild acid-base disorder, a truly normal pH with
distinctly abnormal HCO3- and PaCO2 invariably suggests two
or more primary disorders.
Example: pH 7.40, PaCO2 20 mm Hg, HCO3- 12 mEq/L in a patient with
sepsis. Normal pH results from two co-existing and unstable acid-base
disorders - acute respiratory alkalosis and metabolic acidosis.
Tips to Diagnosing Mixed
Acid-base Disorders
• TIP 3. Simplified rules predict the pH and HCO3- for a
given change in PaCO2. If the pH or HCO3- is higher or
lower than expected for the change in PaCO2, the patient
probably has a metabolic acid-base disorder as well.
•
The next slide shows expected changes in pH and
HCO3- (in mEq/L) for a 10-mm Hg change in PaCO2
resulting from either primary hypoventilation (respiratory
acidosis) or primary hyperventilation (respiratory
alkalosis).
Expected changes in pH and HCO3• for a 10-mm Hg change in PaCO2 resulting from either
primary hypoventilation (respiratory acidosis) or primary
hyperventilation (respiratory alkalosis):
ACUTE
CHRONIC
Resp Acidosis
pH ↓ by 0.07
HCO3- ↑ by 1*
pH ↓ by 0.03
HCO3- ↑ by 3 - 4
Resp Alkalosis
pH ↑ by 0.08
HCO3- ↓ by 2
pH ↑ by 0.03
HCO3- ↓ by 5
* Units for HCO3- are mEq/L
Examples
• A normal or slightly low HCO3- in the presence of hypercapnia
suggests a concomitant metabolic acidosis, e.g., pH 7.27,
PaCO2 50 mm Hg, HCO3- 22 mEq/L. Based on the rule for
increase in HCO3- with hypercapnia, it should be at least 25
mEq/L in this example; that it is only 22 mEq/L suggests a
concomitant metabolic acidosis.
• b)
A normal or slightly elevated HCO3- in the presence of
hypocapnia suggests a concomitant metabolic alkalosis, e.g.,
pH 7.56, PaCO2 30 mm Hg, HCO3- 26 mEq/L. Based on the
rule for decrease in HCO3- with hypocapnia, it should be at
least 23 mEq/L in this example; that it is 26 mEq/L suggests a
concomitant metabolic alkalosis.
Tips to Diagnosing Mixed Acid-base
• TIP 4. In maximally-compensated metabolic acidosis, the
numerical value of PaCO2 should be the same (or close
to) as the last two digits of arterial pH. This observation
reflects the formula for expected respiratory
compensation in metabolic acidosis:
• Expected PaCO2 = [1.5 x serum HCO3] + (8 ± 2)
• Expected PaCo2 in metabolic alkalosis
PCO2 = 0.7 × HCO3 + (21 ± 2)
Acid-base Disorders:
Test Your Understanding
1. A patient’s arterial blood gas shows pH of 7.14, PaCO2
of 70 mm Hg, and HCO3- of 23 mEq/L. How would you
describe the likely acid-base disorder(s)?
2. A 45-year-old man comes to the hospital complaining of
dyspnea for three days. Arterial blood gas reveals pH 7.35,
PaCO2 60 mm Hg, PaO2 57 mm Hg, HCO3- 31 mEq/L.
How would you characterize his acid-base status?
Answers
• 1. Acute elevation of PaCO2 leads to reduced pH, i.e., an
acute respiratory acidosis. However, is the problem only
acute respiratory acidosis or is there some additional
process? For every 10-mm Hg rise in PaCO2 (before any
renal compensation), pH falls about 0.07 units. Because
this patient's pH is down 0.26, or 0.05 more than expected
for a 30-mm Hg increase in PaCO2, there must be an
additional metabolic problem. Also note that with acute
CO2 retention of this degree, the HCO3- should be
elevated 3 mEq/L. Thus a low-normal HCO3- with
increased PaCO2 is another way to uncover an additional
metabolic disorder. Decreased perfusion leading to mild
lactic acidosis would explain the metabolic component.
Answers
• 2.
PaCO2 and HCO3- are elevated, but HCO3- is
elevated more than would be expected from acute
respiratory acidosis. Since the patient has been dyspneic
for several days it is fair to assume a chronic acid-base
disorder. Most likely this patient has a chronic or partially
compensated respiratory acidosis. Without electrolyte
data and more history, you cannot diagnose an
accompanying metabolic disorder.
The alveolar–arterial oxygen tension
difference
• If an arterial blood gas result shows hypoxaemia (low
PaO2) and inadequate alveolar ventilation (high PaCO2),
must be determined whether the hypoxaemia is related to
hypoventilation, or is secondary to a disturbance in
ventilationperfusion, or both. This is assessed by
calculating the difference between the alveolar (PAO2)
and arterial (PaO2) oxygen tensions
The alveolar–arterial oxygen tension
difference
• A normal reference range is 5–15 mmHg
P(A-a)O2
• P(A-a)O2 is the alveolar-arterial difference in partial
pressure of oxygen. It is commonly called the “A-a
gradient,” though it does not actually result from an O2
pressure gradient in the lungs. Instead, it results from
gravity-related blood flow changes within the lungs
(normal ventilation-perfusion imbalance).
• PAO2 is always calculated based on FIO2, PaCO2, and
barometric pressure.
• PaO2 is always measured on an arterial blood sample in
a “blood gas machine.”
•
The alveolar–arterial oxygen tension
difference
• The difference, expressed as P(A–a)O2, increases with
age, cigarette smoking and increasing FiO2. An expected
P(A–a)O2 can be calculated using the formula P(A–a)O2
= 3 + (0.21 x patient's age).
• All causes of hypoxaemia, apart from hypoventilation,
increase the alveolar-arterial difference. In a patient
breathing room air, a P(A–a)O2 greater than 15 mmHg
suggests a ventilationperfusion mismatch related to
disease of the airways, lung parenchyma or pulmonary
vasculature.
Case 1
• . A 55-year-old man is evaluated in the pulmonary lab for
shortness of breath. His regular medications include a
diuretic for hypertension and one aspirin a day. He
smokes a pack of cigarettes a day.
FIO2
.21
HCO3- 30 mEq/L
pH
7.53
PaCO2 37 mm H
Hb
14 gm%
PaO2 62 mm Hg
SaO2 87%
Case 1: discussion
• OXYGENATION: The PaO2 and SaO2 are both reduced
on room air. Since P(A-a)O2 is elevated (approximately
43 mm Hg), the low PaO2 can be attributed to V-Q
imbalance, i.e., a pulmonary problem.
• ACID-BASE: Elevated pH and HCO3- suggest a state of
metabolic alkalosis, most likely related to the patient's
diuretic; his serum K+ should be checked for
hypokalemia.
Case 2
• A 46-year-old man has been in the hospital two days with
pneumonia. He was recovering but has just become
diaphoretic, dyspneic, and hypotensive. He is breathing
oxygen through a nasal cannula at 3 l/min.
• pH
• PaCO2
• PaO2
• SaO2
• Hb
• HCO3-
7.40
20 mm Hg
80 mm Hg
95%
13.3 gm%
12 mEq/L
Case 2: discussion
• OXYGENATION: The PaO2 is lower than expected for
someone hyperventilating to this degree and receiving
supplemental oxygen, and points to significant V-Q
imbalance. The oxygen content is adequate.
• ACID-BASE: Normal pH with very low bicarbonate and
PaCO2 indicates combined respiratory alkalosis and
metabolic acidosis. If these changes are of sudden onset,
the diagnosis of sepsis should be strongly considered,
especially in someone with a documented infection
Case 3:
• A 58-year-old woman is being evaluated in the emergency
department for acute dyspnea.
FIO2
.21
pH
7.19
PaCO2
65 mm Hg
PaO2
45 mm Hg
SaO2
90%
Hb
15.1 gm%
HCO324 mEq/L
Case 3: discussion
• OXYGENATION: The patient's PaO2 is reduced for two
reasons - hypercapnia and V-Q imbalance - the latter
apparent from an elevated P(A-a)O2 (approximately 27
mm Hg).
• ACID-BASE: pH and PaCO2 are suggestive of acute
respiratory acidosis plus metabolic acidosis; the
calculated HCO3- is lower than expected from acute
respiratory acidosis alone.
Case 4
• You are called to see a 40-year-old 60 kg woman who has had a generalized
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tonic-clonic seizure 36 hours after undergoing resection of a tubo-ovarian
abscess. She is poorly arousable, but without focal neurological findings. She has
the following laboratory data:
Na
112 mEq/L,
K
5.0 mEq/L,
Cl
74 mEq/L,
[HC03-] 16 mEq/L,
OSM,
252 mOsm/L,
pH
7.32,
PCO
32. mmHg
You check the preoperative lab results:
Na
124 mEq/L,
K
5.0 mEqn,
Cl
90 mEq/L,
HC03 24 mEqL.
OSM 270 mOsm/L.
What is your diagnosis and what would you do?
Case 4, discussion
• Acute severly symptomatic hyponatremia with
hypotonicity. There has been a large, rapid drop in the
sodium concentration. You check what postop IV fluids
the patient received: 6 liters of D5 0.45% saline over the
last 36 hours. You stop the IV fluids immediately. This
patient had significant hyponatremia on admission:
Preoperatively, the sodium concentration was 124 mEq/L.
Unexplained hyponatremia of this degree should be
carefully evaluated preoperatively if possible.
• This patient has had a marked drop (12 mEq/L) in serum
sodium over a period of only 36 hours, indicating that the
patient's symptoms are due to cerebral edema secondary
to acute hyponatremia. This patient may die if appropriate
management is not begun immediately.
Case4, discussion
• Acid-base disorder.
• Step 1: [HC03-] down, pH down. Metabolic acidosis-most likely
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lactic acidosis.
Step 2: What should the PCO2? 1.5 X 16 + 8 = 32. No
coexisting respiratory disorder.
Step 3: The anion gap of 112 - (12 + 74) = 22 indicates that an
anion gap acidosis is probably present. Comparing the anion
gap with the previous day is very helpful here. The anion gap
was 10 preoperatively. The increase of 12 in the anion gap
indicates an AG acidosis.
in our patient. Therefore, there is no "hidden" metabolic
disorder. The AG acidosis is consistent with a lactic acidosis
(urine ketones are negative).
Answer: Anion gap metabolic acidosis, probably a lactic
acidosis due to the seizure.
Case5,
• A 50-year-old woman was admitted to the hospital with protracted
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nausea, vomiting, and abdominal pain. Abdominal X-rays revealed an
ileus, which resolved with nasogastric suction and IV fluids, She says
that her abdominal pain, which had initially improved with nasogastric
suction and IV fluids, has now returned. She now has a temperature
of 101.6 and her blood pressure has fallen from 130/86 to 86/52. The
abdomen is very tender, and no bowel sounds are present. Her
laboratory studies:
Na 140 mEq/L,
K
4.5 mEq/L,
Cl
80 mEqL,
pH
7.40,
PO2 100 mmHg,
PCO2 40 mmHg,
HCO3- 25 mEq/L.
What is your diagnosis?
Case5, discussion
• Complex acid-base disorder.
• Step 1 : On inspection of the laboratory studies, there is
no obvious acid-base disorder present. are all normal.
• Step 2: Because there is no apparent acid-base disorder
present, appropriateness of compensation is not an issue.
• Step 3: The anion gap is 140 - (25 + 80) = 35! Therefore,
a severe (most likely lactic) anion gap metabolic acidosis
is present. This acidosis is probably the result of bowel
ischemia. Why is the [HC03-] normal? Because there is
an equally profound metabolic alkalosis present, which is
"masking" the metabolic acidosis,
FLUIDS AND
ELECTROLYTES
MALIK ALQUB MD. PhD.
Body Fluids
•Water is most abundant body compound“Average”
body water volume in reference tables based on
healthy, nonobese 70-kg male
•Volume averages 42 L in a 70-kg male
•Plasma (3.5 L)
•Interstitial fluid (10.5 L)
•Intracellular fluid (28 L)
•Water is about 80% of body weight in newborn;
about 60% in adult males; and about 50% in adult
females
OSMOLALITY
• Measure of solution’s ability to create osmotic
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pressure & thus affect movement of water
Number of osmotically active particles per kilogram of
water
Plasma osmolality is 280-300* mOsm/ kg
ECF osmolality is determined by sodium
MEASURE used in clinical practice to evaluate serum &
urine
Osmolality In Clinical Practice
• Serum 280-300mOsm/kg; Urine 50-1400mOsm/kg
• Serum osmolality can be estimated by doubling serum
sodium
• More prescisely
• 2X Na + urea + glucose
• Values are in mmol/L
The Osmolal Gap
• The difference between the measured and the calculated
osmolality is termed the osmolal gap:
• OSM GAP = OSM(meas)- OSM(calc)
• Values of greater than 10 mOsm/L are abnormal and
suggest the presence of an exogenous substance. A
significant increase in the osmolal gap can be helpful as a
clue to the presence of a variety of exogenous
compounds that do not enter into the calculation of
osmolality but are measured as osmotically active by the
lab.
Osmolarity Regulation
• ICF Osm. = ECF Osm.
• Interstitial Osm = Serum Osm.
• Hypothalamus is the serum osmostat. It stimulates thirst
and ADH secretion.
• Primary Defense for
• Primary Defense for
water via ADH effect
Osmolarity = Thirst
Osmolarity = Renal excretion of
Water Losses
• If water is lost, but electrolytes retained, ECF (and ICF)
have higher concentrations, lower volumes
• hypothalamus senses elevated ECF osmolarity this
releases ADH to restore fluid balance
• New water in the ECF will shift into ICF and restore
volumes and concentrations
Severe Water Loss
• Causes:
• excessive perspiration
• inadequate water consumption
• repeated vomiting
• diarrhea
Water Gains
• If water is gained, but electrolytes are not:
• ECF volume increases
• ECF becomes hypotonic to ICF
• fluid shifts from ECF to ICF
• Basically the opposite of water loss:
• may result in overrhydration:
• distorts cells
• changes solute concentrations around enzymes
• disrupts normal cell functions
Water Gains
• If water is gained, but electrolytes are not:
• ECF is at lower concentration, higher
volume
• This triggers decrease in ADH release, fluid
is lost and ICF will lose some water back to
ECF, restoring both volume and
concentration balance
Causes of Overhydration
• Ingestion of large volume of fresh water
• Injection into bloodstream of hypotonic solution
• Endocrine disorders like excessive ADH production
• Inability to eliminate excess water in urine:
• chronic renal failure
• heart failure
• cirrhosis
Disorders of Water Balance:
Figure 26.7a
Hypervolemia
• peripheral and presacral
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edema
pulmonary edema
jugular venous distension
hypertension
Decreased hematocrit
decr. serum protein
Hypovolemia
• poor skin turgor
• dry mucous membranes
• flat neck veins
• hypotension
• increased hematocrit
• Increased serum prot.
pitting edema
jugular venous distension
125
Solutes – dissolved particles
• Electrolytes – charged particles
• Cations – positively charged ions
• Na+, K+ , Ca++, H+
• Anions – negatively charged ions
• Cl-, HCO3- , PO43-
• Non-electrolytes .
• Proteins, urea, glucose, O2, CO2
Rules of Electrolyte Balance
Most common problems with electrolyte
balance are caused by imbalance between
gains and losses of sodium ions
Problems with potassium balance are less
common, but more dangerous than sodium
imbalance
Changes in plasma sodium levels affect:
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•
Plasma volume, blood pressure
ICF and interstitial fluid volumes
Na+, K+
• Sodium holds a central position in fluid and electrolyte
balance
• Sodium is the dominant cation in ECF
• Sodium salts provide 90-95% of ECF osmolarity
(concentration):
• sodium chloride (NaCl)
• sodium bicarbonate
• Sodium concentration in the ECF normally remains stable
• Potassium Is the dominant cation in ICF
SODIUM (NA)
• Main extracellular fluid (ECF) cation
• Helps govern normal ECF osmolality
• Helps maintain acid-base balance
• Activates nerve & muscle cells
• Influences water distribution (with chloride)
Na+ Regulation
So changes
in sodium
concentration
are corrected
by ADH (not
aldosterone)
Figure 27–4
+
Abnormal Na
Concentrations in ECF
• Hyponatremia:
• usu. body water content rises (overhydration)
• Hypernatremia:
• usu. body water content declines (dehydration)
• Severe problems with electrolyte concentrations almost
always occur secondary to fluid balance problems
HYPERNATREMIA
• Serum Na + level > 148 mEq/L
• serum osmolality > 295 mOsm/kg
Hypernatremia from Extrarenal Water
Loss
• The most common causes of hypernatremia due to
extrarenal water loss include fever, profuse sweating,
hyperventilation, including mechanical ventilation, and
severe diarrhea. Patients with hypernatremia caused by
extrarenal water loss often have decreased ECFVs as
well, indicating deficits in total body sodium as well as
water. The proportionally greater deficiency of water than
of sodium leads to the increase in the serum sodium
concentration.
Hypernatremia from Renal Water Loss
• The hallmark of marked renal water loss is polyuria,
defined as a urine volume greater than 3Ll24 hours. The
common defect in all cases of renal water loss is an
inability of the kidney to conserve water appropriately.
There are several important causes of renal water loss.
The key to the evaluation of the patient with renal water
loss is measurement of the urine osmolality.
Diagnosis of Hypernatremia
• Step 1: Reason for water loss or sodium gain?
• Step 2: Reason for inadequate water intake regardless of
source of water loss?
• Step 3: Is polyuria present?
• Urine Osmolality >300 mOsm/L (osmotic diuresis)
• Urine Osm < 150 mOsm/L (diabetes insipidus)
HYPONATREMIA
• Serum Na+ < 135 mEq/L (patient may be asymptomatic until
level drops below 125)
• If hyponatremia develops rapidly, there may be severe
symptoms caused by brain swelling, such as lethargy, coma,
and seizures. If the same degree of hyponatremia develops
slowly over several days, there may be no symptoms at all
Pseudohyponatremia
• Pseudohyponatremia is a very rare situation in which the
serum sodium concentration is found to be low but
extracellular fluid osmolality and tonicity are normal.
• Severe hypertriglyceridemia (triglyceride concentrations in the
thousands of mgldl)
• Severe hyperproteinemia, as may occur in multiple myeloma
(plasma protein concentration > 10 gm/dl)
Hyponatremia with Hypertonicity
• Hyponatremia with hypertonicity is another special case of
hyponatremia, most often caused by severe hyperglycernia in
uncontrolled diabetes mellitus. The sodium is low because of
transcellular shifting of water, but both tonicity and measured
serum osmolality are very high. Because glucose is an effective
osmole, the high glucose concentration causes water
movement from the intracellular compartment to the
extracellular compartment, thereby reducing the extracellular
sodium concentration. Consequently, the sodium concentration
decreases, even though the tonicity of the ECFV is increased.
The sodium concentration falls by approximately 1.6 mEq/L for
every increase of 100 mg/dl in glucose concentration above
100 mg/dl. To make the diagnosis of hyponatremia with
hypertonicity, measured osmolality must be clearly elevated by
the hyperglycemia.
Hyponatremia with Hypotonicity ("True"
Hyponatremia)
• Hyponatremia with hypotonicity is by far the most
common form of hyponatremia and results from
• impaired renal water excretion in the presence of
• continued water intake.
• Hyponatrernia with hypotonicity requires two things:
• Impaired renal water excretion
• Continued water intake
Approach to the Patient with
Hyponatremia
• Exclude pseudohyponatremia and hyponatremia with
increased tonicity
• Investigate hyponatremia with hypotonicity. Begin by
asking two key questions:
• (1) Why is renal water excretion impaired?
• (2) What is the patient's source of excess free water?
What are the IV fluids?
A step-by-step approach to diagnosis: Find
the reason for impaired water excretion.
• Step 1: Is renal failure present?
• Step 2: Are there signs of ECFV depletion?
• Step 3: Are there signs of ECFV overload?
• Step 4: Is the patient taking thiazide diuretics?
• Step 5: Is there a condition or drug capable of producing
SIADH (Fig. 3-2)?
• Step 6: Is there evidence of thyroid or adrenal
insufficiency?
• Step 7: Elderly/poor solute intake?
Potassium Balance
• 98% of potassium in the human body is in ICF
• Cells expend energy to recover potassium ions diffused
from cytoplasm into ECF
• Factors
• Rate of gain across digestive epithelium
• Rate of loss into urine, regulated along distal portions of nephron
and collecting system as Na+ from tubular fluid is exchanged for K+
in peritubular fluid
POTASSIUM (K+)
• DOMINANT
INTRACELLULAR
ELECTROLYTE
• NL SERUM LEVEL
3.5-5.5 *mEq/L
POTASSIUM (K)
• Dominant cation in intracellular fluid (ICF)
• Regulates cell excitability
• Permeates cell membranes, thereby affecting cell’s
electrical status
• Helps control ICF osmolality & ICF osmotic pressure
HYPERKALEMIA
• K+ > 5.5 mEq/L
• Dangerous due to potential for fatal dysrhythmias,
cardiac arrest
• Major cause is renal disease
• Beware of pseudohyperkalemia due to prolonged
tourniquet, hemolysis of blood, sampling above
KCl infusion
HYPERKALEMIA
• Severe hyperkalemia may be a medical emergency
requiring immediate treatment, depending upon the
nature of any ECG abnormalities. Clinical manifestations
of hyperkalemia usually occur when the potassium
concentration is >6.5 mEq/L and include:
• Neuromuscular signs (weakness, ascending paralysis,
and respiratory failure)
• Typical progressive ECG changes with increasing
potassium concentration: peaked T waves, flattened P
waves, prolonged PR interval.
• The cardiac changes may occur suddenly and without
warning.
Pseudohyperkalemia
• In pseudohyperkalemia, the potassium concentration is
artifactually high, in addition to simple lab error, consist of
marked thrombocytosis (platelet count > 1,000,000);
severe leukocytosis (white blood cell count >200,000);
mononucleosis; ischemic blood drawing, hemolysis during
blood drawing; and a rare condition known as familial
pseudohyperkalemia, in which potassium "leaks" out of
red blood cells while the blood is waiting to be analyzed
Redistribution Hyperkalemia
• Redistribution hyperkalemia is caused by potassium
transiently leaving cells, thereby raising the serum
potassium concentration. Total body potassium need not
be increased for redistribution hyperkalemia to develop.
Only a small amount of potassium is located in the
extracellular compartment (about 56 mEq in a 70 kg man,
compared to a total body potassium content of around
4200 mEq/L for this individual). Consequently, a relatively
small shift of potassium from the intracellular space to the
extracellular space can cause a large increase in plasma
potassium concentration.
Hyperkalemia Secondary to Impaired
Potassium Excretion
• The majority of cases of hyperkalemia secondary to true
excess of total body potassium are due to a defect in
renal potassium excretion in the presence of ongoing
potassium intake. The impaired renal potassium excretion
is due to one or both of the following:
• Aldosterone deficiency or tubular unresponsiveness to
aldosterone
• Renal failure (reduced GFR)
.
Aldosterone Deficiency and Aldosterone
Unresponsiveness
• True potassium excess (increased total body potassium)
due to renal retention of potassium will develop if there is
a deficiency of aldosterone, or tubular unresponsiveness
to the kaliuretic effects of aldosterone.
HYPOKALEMIA
• K+ < 3.5mEq/L
• Most common type of electrolyte imbalance
• Major cause is increase renal loss most often
associated with diuretics
• Can increase the action of digitalis
• The clinical consequences of significant hypokalemia
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include:
Neuromuscular manifestations (weakness, fatigue,
paralysis, respiratory muscle dysfunction,
rhabdomyolysis)
Gastrointestinal manifestations (constipation, ileus)
Nephrogenic diabetes insipidus
ECG changes (prominent U waves, T wave flattening, ST
segment changes) Cardiac arrhythmias (especially with
concurrent digitalis)
Spurious Hypokalemia
• In spurious hypokalemia, the potassium concentration is
not really low.
• Marked leukocytosis (> 100,000) rarely may produce
spurious hypokalemia if the blood tube is allowed to sit at
room temperature. White cells may simply take up the
potassium in the blood specimen.
• A dose of insulin right before blood drawing could cause
temporary movement of potassium into cells in the blood
tube and falsely lower the serum potassium. The
magnitude of the fall in potassium is generally small
(around 0.3 mEq/L).
Redistribution Hypokalemia
• Redistribution hypokalemia is caused by the entry of
potassium into cells. Only a small amount of total body
potassium is located in the extracellular compartment.
Consequently, a small shift of potassium from the
extracellular space to the intracellular space can cause a
large change in plasma potassium concentration.
Renal Potassium Depletion
• Many of the disorders causing renal potassium loss (urine
potassium >20 mEq/24 hours in a patient with
hypokalemia) are also associated with acid-base
disorders. Therefore, it is customary to classify the
numerous causes of renal
• potassium loss according to whether they typically occur
together with
• Metabolic acidosis
• Metabolic alkalosis
• No specific acid-base disorder
KIDNEY FUNCTION
TESTING
MALIK ALQUB MD. PhD.
Kidney structure
• A) Glomerular
Capsule
• B) Renal Tubule
proximal convoluted
tubule
• loop of Henle
• distal convoluted tubule
•
• C) Collecting Duct
•
Urine Formation
• Urine formation requiers :
• Glomerular Filtration : Due to differences in pressure water,
small molecules move from the glomerulus capillaries into the
glomerular capsule
• Tubular reabsorption: many molecules are reabsorbed from
the nephron into the capillary (diffusion, facilitated diffusion,
osmosis, and active transport), i.e. Glucose is actively
reabsorbed with transport carriers. If the carriers are
overwhelmed glucose appears in the urine indicating diabetes
• Tubular secretion: Substances are actively removed from
blood and added to tubular fluid (active transport), ie. H+,
creatinine, and some drugs are moved by active transport
from the blood into the distal convoluted tubule
Urine Formation
Biochemical Tests of Renal Function
• Measurement of GFR
• Clearance tests
• Plasma creatinine
• Urea
• Renal tubular function tests
• Specific proteinurea
• Urine dilution test
• Urinalysis
When should you assess renal function?
• Older age
• Family history of Chronic Kidney disease (CKD)
• Decreased renal mass
• Low birth weight
• Diabetes Mellitus (DM)
• Hypertension (HTN)
• Autoimmune disease
• Systemic infections
• Urinary tract infections (UTI)
• Nephrolithiasis
• Obstruction to the lower urinary tract
• Drug toxicity
Biochemical Tests of Renal Function
• Measurement of GFR
• Clearance tests
• Plasma creatinine
• Urea
Measurement of glomerular filtration rate
• GFR can be estimated by measuring the urinary excretion of a
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substance that is completely filtered from the blood by the
glomeruli and it is not secreted, reabsorbed or metabolized by
the renal tubules.
Clearance is defined as the (hypothetical) quantity of blood or
plasma completely cleared of a substance per unit of time.
Clearance of substances that are filtered exclusively or
predominantly by the glomeruli but neither reabsorbed nor
secreted by other regions of the nephron can be used to
measure GFR.
The Volume of blood from which inulin is cleared or completely
removed in one minute is known as the inulin clearance and is
equal to the GFR.
Measurement of inulin clearance requires the infusion of inulin
into the blood and is not suitable for routine clinical use
Inulin Clearance Test
• advantages
• Neither reabsorbed nor secreted
• Ideal substance to measure GFR
• Disadvantages:
• Need for intravenous administration
• Technical difficulty of the analysis
• GFR = (U x V) /P
• Normal Value: 120ml/min.
Creatinine
• 1 to 2% of muscle creatine spontaneously converts to
creatinine daily and released into body fluids at a constant
rate.
• Endogenous creatinine produced is proportional to
muscle mass, it is a function of total muscle mass the
production varies with age and sex
• Dietary fluctuations of creatinine intake cause only minor
variation in daily creatinine excretion of the same person.
• Creatinine released into body fluids at a constant rate
and its plasma levels maintained within narrow limits
Creatinine clearance may be measured as an indicator of
GFR.
Creatinine clearance and clinical utility
• The most frequently used clearance test is based on the
measurement of creatinine.
• Small quantity of creatinine is reabsorbed by the tubules
and other quantities are actively secreted by the renal
tubules, So creatinine clearance is approximately 7%
greater than inulin clearance.
• The difference is not significant when GFR is normal but
when the GFR is low (less 10 ml/min), tubular secretion
makes the major contribution to creatinine excretion and
the creatinine clearance significantly overestimates the
GFR.
Creatinine clearance clinical utility
• An estimate of the GFR can be calculated from the
creatinine content of a 24-hour urine collection, and the
plasma concentration within this period.
• The volume of urine is measured, urine flow rate is
calculated (ml/min) and the assay for creatinine is
performed on plasma and urine to obtain the
concentration in mg per dl or per ml.
• Creatinine clearance in adults is normally about of 120
ml/min,
• The accurate measurement of creatinine clearance is
difficult, especially in outpatients, since it is necessary to
obtain a complete and accurately timed sample of urine
Creatinine clearance clinical utility
• Creatinine clearance (mL/min) = (uCr x uV)/(sCr x 1440)
• l. Where uCr is urine creatinine in mg/dL
• 2. Where sCr is serum creatinine in mgldL
• 3. Where uV is 24-h urine volume in mL
• 4. Where 1440 represents number of minutes in 24 h
Creatinine clearance and clinical utility
• The 'clearance' of creatinine from plasma is directly
related to the GFR if:
• The urine volume is collected accurately
• There are no ketones or heavy proteinuria present to
interfere with the creatinine determination.
• It should be noted that the GFR decline with age (to a
greater extent in males than in females) and this must be
taken into account when interpreting results.
Use of Formulae to Predict Clearance
• Equations include factors related to creatinine generation
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and excretion (age, sex, race, body size)
Rely on patients being in steady state
Major limitation is due to variation in
Cockcroft-Gault equation predicts Ccr as
Creatinine clearance (mL/min) = (140-age) x lean body
weight (kg)/plasma creatinine (mg/dL) x 72
(multiply by 0.85 if female)
• Modifications required for children & obese subjects
• Can be modified to use Surface area
Plasma Urea
Urea is the major nitrogen-containing metabolic product of protein
catabolism in humans,
Its elimination in the urine represents the major route for nitrogen
excretion.
More than 90% of urea is excreted through the kidneys, with losses
through the GIT and skin
 Urea is filtered freely by the glomeruli
Plasma urea concentration is often used as an index of renal
glomerular function
Urea production is increased by a high protein intake and it is
decreased in patients with a low protein intake or in patients with liver
disease.
Plasma Urea
• Many renal diseases with various glomerular, tubular, interstitial or
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vascular damage can cause an increase in plasma urea
concentration.
The reference interval for serum urea of healthy adults is 5-39 mg/dl.
Plasma concentrations also tend to be slightly higher in males than
females. High protein diet causes significant increases in plasma urea
concentrations and urinary excretion.
Measurement of plasma creatinine provides a more accurate
assessment than urea because there are many factors that affect
urea level.
Nonrenal factors can affect the urea level (normal adults is level 5-39
mg/dl) like:
Mild dehydration,
high protein diet,
increased protein catabolism, muscle wasting as in starvation,
reabsorption of blood proteins after a GIT haemorrhage,
treatment with cortisol or its synthetic analogous
Clinical Significance
• States associated with elevated levels of urea in blood are
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referred to as uremia or azotemia.
Causes of urea plasma elevations:
Prerenal: renal hypoperfusion
Renal: acute tubular necrosis
Postrenal: obstruction of urinary flow
BUN / Creatinine Ratio
• The blood urea nitrogen (BUN)-creatinine ratio. the usual
value of about 10:1. for reasons as yet unclear, tubular
reabsorption of urea nitrogen is enhanced in low-urine flow
states. Thus, a high BUN-creatinine ratio often occurs in
prerenal and postrenal forms of renal failure. Similarly,
enhanced delivery of amino acids to the liver (as with
catabolism, corticosteroids, etc.) can enhance urea
nitrogen formation and increase the BUN-creatinine ratio.
A BUN-creatinine ratio lower than 10:1 can occur because
of decreased urea nitrogen formation (eg, in protein
malnutrition, advanced liver disease), enhanced creatinine
formation (eg, with rhabdomyolysis), impaired tubular
secretion of creatinine (eg, secondary to trimethoprim,
cimetidine,
Prerenal azotemia
• Prerenal azotemia refers to elevations in BUN and
creatinine levels resulting from problems in the systemic
circulation that decrease flow to the kidneys. In prerenal
azotemia, decreased renal flow stimulates salt and water
retention to restore volume and pressure.
• Constriction of the afferent arterioles causes a decrease
in intraglomerular pressure, which reduces the GFR
proportionally. Renin converts angiotensin I to angiotensin
II, which, in turn, stimulates aldosterone release.
Increased aldosterone levels results in salt and water
absorption in the distal collecting tubule.
Prerenal azotemia
• Volume depletion
• Renal losses (diuretics, polyuria)
• GI losses (vomiting, diarrhea)
• Cutaneous losses (burns, Stevens-Johnson syndrome)
• Hemorrhage
• Pancreatitis
• Decreased cardiac output
• Heart failure
• Pulmonary embolus
• Acute myocardial infarction
• Severe valvular heart disease
• Abdominal compartment syndrome (tense ascites
Renal Azotemia
• Intrarenal azotemia, also known as acute renal failure
(ARF), renal-renal azotemia, and acute kidney injury
(AKI), refers to elevations in BUN and creatinine resulting
from problems in the kidney itself. There are several
definitions, including a rise in serum creatinine levels of
about 30% from baseline or a sudden decline in output
below 500 mL/day. If output is preserved, AKI is
nonoliguric; if output falls below 500 mL/day, ARF is
oliguric. Any form of AKI may be so severe that it virtually
stops formation; this condition is called anuria (< 100
mL/day).
Renal Azotemia
• Intrarenal azotemia occurs as a result of injury to the
glomeruli, tubules, interstitium, or small vessels. It may be
acute oliguric, acute nonoliguric, or chronic. Systemic
disease, nocturia, proteinuria, loss of urinary
concentrating ability (low urine specific gravity), anemia,
and hypocalcemia are suggestive of chronic intrarenal
azotemia.
Postrenal azotemia
• Postrenal azotemia refers to elevations in BUN and creatinine levels
resulting from obstruction in the collecting system. Obstruction to flow
leads to reversal of the Starling forces responsible for glomerular
filtration. Progressive bilateral obstruction causes hydronephrosis with
an increase in the Bowman capsular hydrostatic pressure and tubular
blockage that leads to progressive decline in and ultimate cessation
of glomerular filtration, azotemia, acidosis, fluid overload, and
hyperkalemia.
• Unilateral obstruction rarely causes azotemia. There is evidence that
if complete ureteral obstruction is relieved within 48 hours of onset,
relatively complete recovery of GFR can be achieved within a week;
little or no further recovery occurs after 12 weeks. Complete or
prolonged partial obstruction can lead to tubular atrophy and
irreversible renal fibrosis. Hydronephrosis may be absent if
obstruction is mild or acute or if the collecting system is encased by
retroperitoneal tumor or fibrosis.
Postrenal azotemia
• Obstruction of ureters, bilateral
• Extraureteral
•
Tumor: cervix, prostate, endometriosis
•
Periureteral fibrosis
•
Accidental ureteral ligation during pelvic
•
operation
• Intraureteral
•
Sulfonamide and uric acid crystals
•
Blood clots
•
Pyogenic debris
•
Stones
•
Edema
•
Papillary necrosis
• Bladder neck obstruction
• Prostatic hypertro
• Bladder carcinoma
• Bladder infection
• Functional: neuropathy or ganglionic
• blocking agents
Definition of acute renal failure
• Acute renal failure (ARF) has traditionally been defined
as the abrupt loss of kidney function that results in the
retention of urea and other nitrogenous waste products
and in the dysregulation of extracellular volume and
electrolytes. The loss of kidney function is most easily
detected by measurement of the serum creatinine which
Is used to estimate the glomerular filtration rate (GFR)
Etiology of ARF
Diagnostic criteria of ARF
• The presence of AKI is usually inferred by an elevation in
the SCr concentration. AKI is currently defined by a rise
from baseline of at least 0.3 mg/dL within 48 h or at least
50% higher than baseline within 1 week, or a reduction in
urine output to less than 0.5 mL/kg per hour for longer
than 6 h.
• normal Cr:
• Female 50-90 µmol/L
• Male 70-120 µmol/L
Fractional excretion of sodium
UNa x PCr
• FENa = --------------- x 100
PNa x UCr
• Interpretation
• <1% – prerenal, glomerulonephritis, obstruction
• >2% – ATN
• 1-2% - either prerenal or ATN
• Not accurate before diuretics or IVF
The definition of chronic kidney disease
• Evidence of structural or functional kidney abnormalities
(abnormal urinalysis, imaging studies, or histology) that
persist for at least three months, with or without a
decreased GFR. The most common manifestation of
kidney damage is persistent albuminuria, including
microalbuminuria.
• OR
• Decreased GFR, with or without evidence of kidney
damage. GFR < 60 ml/min/1.73m2 for  3
month
Who are at Risk for CKD
• Diabetes
• Hypertension
• Age , Family H/o Kidney Disease
• Systemic Infections
• Recurrent UTI
• Urinary Stone Disease
• Loss of Renal mass
• Neoplasia of any part
• Nephrotoxic Drugs (NSAIDs)
The Two Most Common Causes of CKD
Other
10%
Diabetes
50.1%
Glomerulonephritis
13%
Hypertension
27%
CKD Clinical Stages
Stage Description
GFR
(ml/min/1.73 m2)
1
Kidney damage with normal or ↑ GFR
 90
2
Kidney damage with mild  GFR
60-89
3
Kidney damage with moderate  GFR
30-59
4
Severe  GFR
15-29
5
Kidney Failure (ESRD)
< 15 (or dialysis)
Biochemical Tests of Renal Function
• Renal tubular function tests
• Specific proteinurea
• Urine dilution test
Proteinuria
The glomerular basement membrane does not usually allow passage
of albumin and large proteins. A small amount of albumin, usually less
than 25 mg/24 hours, is found in urine.
Urinary protein excretion in the normal adult should be less
than 150 mg/day.
When larger amounts, in excess of 250 mg/24 hours, are detected,
significant damage to the glomerular membrane has occurred.
Quantitative urine protein measurements should always be made on
complete 24-hour urine collections.
Albumin excretion in the range 25-300 mg/24 hours is termed
microalbuminuria
Proteinuria
• Normal < 150 mg/24h.
• TYPES OF PROTEINURIA
• Glomerular proteinuria
• Tubular proteinuria
• Overflow proteinuria
Glomerular proteinuria
• Glomerular proteinuria — Glomerular proteinuria is due to
increased filtration of macromolecules (such as albumin)
across the glomerular capillary wall. The proteinuria
associated with diabetic nephropathy and other
glomerular diseases, as well as more benign causes such
as orthostatic or exercise-induced proteinuria fall into this
category. Most patients with benign causes of isolated
proteinuria excrete less than 1 to 2 g/day
Tubular proteinuria
• Low molecular weight proteins — such as ß2-
microglobulin, immunoglobulin light chains, retinol-binding
protein, and amino acids — have a molecular weight that
is generally under 25,000 in comparison to the 69,000
molecular weight of albumin. These smaller proteins can
be filtered across the glomerulus and are then almost
completely reabsorbed in the proximal tubule.
Interference with proximal tubular reabsorption, due to a
variety of tubulointerstitial diseases or even some primary
glomerular diseases, can lead to increased excretion of
these smaller proteins
Overflow proteinuria
• Increased excretion of low molecular weight proteins can
occur with marked overproduction of a particular protein,
leading to increased glomerular filtration and excretion.
This is almost always due to immunoglobulin light chains
in multiple myeloma, but may also be due to lysozyme (in
acute myelomonocytic leukemia), myoglobin (in
rhabdomyolysis), or hemoglobin (in intravascular
hemolysis
Concentration and Dilution of the Urine
• Maximal urine concentration
• = 1200 - 1400 mOsm / L
• (specific gravity ~ 1.030
• Minimal urine concentration
• = 50 - 70 mOsm / L
• (specific gravity ~ 1.003)
How the Test is Performed
• Water loading. Drinking large amounts of water or
receiving fluids through a vein.
• Water deprivation. Not drinking fluids for a certain amount
of time.
• ADH administration. Receiving antidiuretic hormone
(ADH), which should cause the urine to become
concentrated.
Urine Dilution Test
• Bladder is Emptied.
• 1,000 to 1,200 ml of water is given to the patient.
• Urine sample is collected every hour for the next 4 hours.
• Specific gravity is measured
• If the functioning of renal tubule is normal, the urinary
specific gravity should fall to 1.005 or less.
• It the renal tubules are diseased, the concentration of the
solutes in urine will remain constant irrespective of excess
water intake.
KIDNEY FUNCTION
TESTING: URINE
ANALYSIS
MALIK ALQUB MD. PhD.
Specimen Collection
• A midstream clean-catch technique usually is adequate in
•
•
•
•
men and women. Although prior cleansing of the external
genitalia often is recommended in women, it has no
proven benefit.
delays of more than two hours between collection and
examination often cause unreliable results
The first voided morning urine (the most common)
Random urine (for emergency)
Clean-catch, midstream urine (for urine culture)
Color and Odor
• Odor:
• Ammonia-like:
•
•
•
•
•
•
•
•
•
(Urea-splitting bacteria)
Foul, offensive: Old specimen, pus or inflammation
Sweet:
Glucose
Fruity:
Ketones
Maple syrup-like: Maple Syrup Urine Disease
Color:
Colorless
Diluted urine
Deep Yellow
Concentrated Urine, Riboflavin
Yellow-Green
Bilirubin / Biliverdin
Red Blood /
Hemoglobin
volume
• Oliguria: This refers to reduced urine output, usually defined as <400
mL/d. Oligoanuria refers to a more marked reduction in urine output,
i.e., <100 mL/d. Anuria indicates the complete absence of urine
output. Oliguria most often occurs in the setting of volume depletion
and/or renal hypoperfusion, resulting in "prerenal azotemia" and acute
renal failure . Anuria can be caused by complete bilateral urinary tract
obstruction; a vascular catastrophe (dissection or arterial occlusion);
renal vein thrombosis; renal cortical necrosis; severe acute tubular
necrosis; nonsteroidal antiinflammatory drugs, angiotensin-converting
enzyme (ACE) inhibitors, and/or angiotensin receptor blockers; and
hypovolemic, cardiogenic, or septic shock. Oliguria is never normal,
because at least 400 mL of maximally concentrated urine must be
produced to excrete the obligate daily osmolar load.
• Polyuria is defined as a urine output >3 Lid. It is often
accompanied by nocturia and urinary frequency and must
be differentiated from other more common conditions
associated with lower urinary tract pathology and urinary
urgency or frequency (e.g., cystitis, prostatism). It is often
accompanied by hypernatremia. Polyuria can occur as a
response to a solute load (e.g., hyperglycemia) or to an
abnormality in arginine vasopressin (A VP; also known as
antidiuretic hormone [ADH]) action.
SPECIFIC GRAVITY
• Urinary specific gravity (USG) correlates with urine
osmolality and gives important insight into the patient’s
hydration status. It also reflects the concentrating ability of
the kidneys.
• Normal USG can range from 1.003 to 1.030;
• a value of less than 1.010 indicates relative hydration, and
• a value greater than 1.020 indicates relative dehydration..
SPECIFIC GRAVITY
• Increased USG is associated with
• glycosuria
• syndrome of inappropriate antidiuretic hormone;
• decreased USG is associated with
• diuretic use,
• diabete insipidus,
• adrenal insufficiency,
• aldosteronism,
• impaired renal function.
•
In patients with intrinsic renal insufficiency, USG is
fixed at 1.010—the specific gravity of the glomerular
filtrate
URINARY PH
• Urinary pH can range from 4.5 to 8 but normally 5.5 to6.5
• Urinary pH generally reflects the serum pH, except in
patients with renal tubular acidosis (RTA).
• Alkaline urine in a patient with a UTI suggests the
presence of a urea-splitting organism,
HEMATURIA
• The presence of three or more red blood cells (RBCs) per
high-powered field (HPF) in two of three urine samples is
the generally accepted definition of hematuria
• The dipstick test for blood detects the peroxidase activity
of erythrocytes. However, myoglobin and hemoglobin also
will catalyze this reaction, so a positive test result may
indicate hematuria, myoglobinuria, or hemoglobinuria
• Visualization of intact erythrocytes on microscopic
examination of the urinary sediment can distinguish
hematuria from other conditions.
Glomerular Hematuria
• Glomerular hematuria typically is associated with
significant proteinuria, erythrocyte casts, and dysmorphic
RBCs, IgA nephropathy (i.e., Berger’s disease) is the
most common cause of glomerula hematuria.
Renal (Nonglomerular) Hematuria
• Nonglomerular hematuria is secondary to
tubulointerstitial, renovascular, or metabolic disorders.
Like glomerular hematuria, it often is associated with
significant proteinuria; however, there are no associated
dysmorphic RBCs or erythrocyte casts.
Urologic Hematuria
• Urologic causes of hematuria include tumors, calculi, and
infections. Urologic hematuria is distinguished from other
etiologies by the absence of proteinuria, dysmorphic
RBCs, and erythrocyte casts.
• Exercise-induced hematuria is a relatively common,
benign condition that often is associated with longdistance
running. Results of repeat urinalysis after 48 to 72 hours
should be negative in patients with this condition
PROTEINURIA
• Normal urinary proteins include albumin, serum globulins,
and proteins secreted by the nephron. Proteinuria is
defined as urinary protein excretion of more than 150 mg
per day (10 to 20 mg per dL) and is the hallmark of renal
disease.
• Microalbuminuria is defined as the excretion of 30 to 150
mg of protein per day and is a sign of early renal disease,
particularly in diabetic patients.
GLYCOSURIA
• Glucose normally is filtered by the glomerulus, but it is
almost completely reabsorbed in the proximal tubule.
Glycosuria occurs when the filtered load of glucose
exceeds the ability of the tubule to reabsorb it (i.e., 180 to
200 mg per dL).
• 1.hyperglycemia: diabetes mellitus
•
Cushing’s syndrom
• 2.without hyperglycemia: renal tubular dysfunction, such
as pyelonephritis
KETONURIA
• Ketonuria most commonly is associated with uncontrolled
diabetes, but it also can occur during pregnancy,
carbohydrate-free diets, and starvation.
NITRITES
• Nitrites normally are not found in urine but result when
bacteria reduce urinary nitrates to nitrites. Many gram
negative and some gram-positive organisms are capable
of this conversion, and a positive dipstick nitrite test
indicates that these organisms are present in significant
numbers (i.e., more than 10,000 per mL). This test is
specific but not highly sensitive,
LEUKOCYTE ESTERASE
• Leukocyte esterase is produced by neutrophils and may
signal pyuria associated with UTI. To detect significant
pyuria accurately, five minutes should be allowed for the
dipstick reagent strip to change color.
• Leukocyte casts in the urinary sediment can help localize
the area of inflammation to the kidney.
BILIRUBIN AND UROBILINOGEN
• Urine normally does not contain detectable amounts of
bilirubin. Unconjugated bilirubin is water insoluble and
cannot pass through the glomerulus; conjugated bilirubin
is water soluble and indicates further evaluation for liver
dysfunction and biliary obstruction when it is detected in
the urine. Normal urine contains only small amounts of
urobilinogen, the end product of conjugated bilirubin after
it has passed through the bile ducts and been
metabolized in the intestine. Urobilinogen is reabsorbed
into the portal circulation, and a small amount eventually
is filtered by the glomerulus. Hemolysis and
hepatocellular disease can elevate urobilinogen levels,
and antibiotic use and bile duct obstruction can
decrease urobilinogen levels.
Microscopic Urinalysis
• CELLS: Leukocytes, Epithelial cells often are present, The
presence of renal tubule cells indicates significant renal
pathology, Erythrocytes,
• CASTS: Their cylindrical shape reflects the tubule in
which they were formed and is retained when the casts
are washed away.
• CRYSTALS: Calcium oxalate crystals, Uric acid crystals,
Triple phosphate crystals, Cystine crystals,
LABORATORY
ASSESMENT OF
BLEEDING
Malik ALQUB. MD. Ph.D.
Components of normal haemostasis
• Blood vessels
• Endothelial cells
• Sub-endothelial surface
• Platelets: primary haemostasis
• Platelet membrane
• Platelet granules
• Coagulation factors
• Fibrinolytic pathway
• Naturally occurring inhibitors of coagulation
Haemostatic response to vessel injury
Haemostasis
• Primary Hemostasis
• Platelet Plug Formation
• Dependent on normal platelet number & function
• Initial Manifestation of Clot Formation
• Secondary Hemostasis
• Activation of Clotting Cascade, Deposition & Stabilization of
Fibrin
• Tertiary Hemostasis
• Dissolution of Fibrin Clot
• Dependent on Plasminogen Activation
Primary Hemostasis
• vasoconstriction (vascular system)
• platelet exposure to subendothelial connective tissue of
blood vessels
• Platelet release of ADP, ATP, Thromboxane A2
(promotes vasoconstriction)
• Platelet aggregation, phospholipid provides site for fibrin
formation
Secondary hemostasis
• Intrinsic Pathway
• All components required for initiating this pathway are
circulating in the blood
• triggered by contact with collagen or glass
• Extrinsic Pathway
• Initiated by the release of tissue thromboplastin and calcium
from damaged tissue
• Common Pathway
• Leads to clot formation including the platelet plug and fibrin
produced
Coagulation Proteins
• Zymogens
• enzyme precursors II, VII, IX, X, XI, XII, Prekallkrein
• When activated become serine proteases
• Cofactors
• Nonenzymatic V, VIII, HMWK, Tissue factor(thromboplastin)
• Kinin factors prekallikrein, kallikrein, HMWK
• Roles include coag activation as well as fibrinolytic activation
Coagulation made easy
The PTT Pathway
The PT Pathway
Coagulation made easy
The PTT Pathway
The PT Pathway
X
The PT and the PTT
pathway meet at factor X,
because “X” marks the
spot
Coagulation made easy
The PTT Pathway
The PT Pathway
V
X
Factor V is a cofactor for
factor X, and you can
remember this because V
fits into the notch of the X
Coagulation made easy
The PTT Pathway
The PT Pathway
V
X
Prothrombin
Thrombin
Factor Xa converts prothrombin (Factor II) into
thrombin, the most important enzyme on the planet
Coagulation made easy
The PTT Pathway
The PT Pathway
V
X
Prothrombin
Fibrinogen
Thrombin, among other
things, converts the
soluble molecule
fibrinogen into a solid fibrin
clot
Thrombin
Fibrin
Coagulation made easy the PT
PT has one less letter than PTT,
and PT values are shorter than
PTT values, because the
pathway is shorter. It means
that the PT pathway is also
shorter and this is lucky, so the
lucky PT pathway uses lucky
factor 7 to activate factor X
The PT Pathway
7
V
X
Prothrombin
Fibrinogen
Thrombin
Fibrin
Coagulation made easy - the aPTT
The PTT Pathway
XII
The PTT pathway has all those
hideous roman numerals. . .
How are we going to remember
them? Hmmmmm. . . . . . .
XI
IX
VIII
V
X
Prothrombin
Fibrinogen
Thrombin
Fibrin
Coagulation made easy - the aPTT
The PTT Pathway
T
Well, just remember that the
PTT is a basic TENET of
hematology.
TENET stands for. . . . . .
E
N
E
T
V
X
Prothrombin
Fibrinogen
Thrombin
Fibrin
Coagulation made easy - the
aPTT
The PTT Pathway
Twelve
Eleven
Nine
Eight
Ten
V
X
Prothrombin
Fibrinogen
Thrombin
Fibrin
Coag Made Easy: PT and PTT both
Prolonged
The PTT Pathway
The PT Pathway
V
X
Prothrombin (II)
Fibrinogen
These factors are in the
common pathway
Coag Made Easy: Only PT Prolonged
7
Deficiency of Factor VII will prolong the PT but not the PTT
Coag Made Easy: Only PTT Prolonged
Twelve
Eleven
Nine
Eight
Ten
Deficiencies of Factors 12, 11, 9
and 8 will prolong the PTT and
not the PT. Remember that
factor 10 is in the common
pathway, and affects BOTH the
PT and the PTT
FIBRINOLYTIC SYSTEM
• Definition: temporary fibrin clot systematically and
gradually dissolved as the vessel heals
• Key components
•
•
•
•
•
•
Plasminogen (inactive form)
Plasminogen activators
Plasmin
Fibrin
Fibrin Degradation Products (FDP)
Inhibitors of plasminogen activators and plasmin
Activators of Fibrinolysis
• Intrinsic activators
• Factor XIIa, XIa, kallikrein
• Extrinsic activators
• Tissue type plasminogen activator (t-PA)
• Urokinase type plasminogen acitvator
(u-PA)
• Exogenous activators
• Streptokinase (derived from beta strep)
FIBRINOLYSIS
Antithrombin
• Also known as Antithrombin III
• Inhibits coagulation by irreversibly binding the
thrombogenic proteins thrombin (IIa), IXa, Xa, XIa and
XIIa
• Antithrombin’s binding reaction is amplified 1000-fold
by heparin, which binds to antithrombin to cause a
conformational change which more avidly binds
thrombin and the other serine proteases
Protein C and S
• Protein C is a vitamin K dependent glycoprotein produced in the liver
• In the activation of protein C, thrombin binds to thrombomodulin, a
•
•
•
•
structural protein on the endothelial cell surface
This complex then converts protein C to activated protein C (APC),
which degrades factors Va and VIIIa, limiting thrombin production
For protein C to bind, cleave and degrade factors Va and VIIIa,
protein S must be available
Protein C deficiency, whether inherited or acquired, may cause
thrombosis when levels drop to 50% or below
Protein C deficiency also occurs with surgery, trauma, pregnancy,
OCP, liver or renal failure, DIC,or warfarin
Protein S
• Protein S is an essential cofactor in the protein C
pathway
• Inherited PS deficiency is an autosomal dominant
disorder, causing thrombosis when levels drop to 50%
or lower
• Functional PS activity may be decreased in vitamin K
deficiency, warfarin, liver disease
• Increased PS consumption occurs in acute thrombosis,
DIC, MPD, sickle cell disease
Activated Protein C (APC) Resistance
Due to Factor V Leiden
• Activated protein C (APC) is the functional form of the
naturally occurring, vitamin K dependent anticoagulant,
protein C
• APC is an anticoagulant which inactivates factors Va
and VIIIa in the presence of its cofactor, protein S
• Alterations of the factor V molecule at APC binding sites
(such as amino acid 506 in Factor V Leiden) impair, or
resist APC’s ability to degrade or inactivate factor Va
VIIIa
Va
Protein S
IIa
Thrombin
Anti-coagulant
effects
Activated
Protein C
Protein C
IIa
thrombomodulin
Protein C Anticoagulant Pathway
What is factor V?
FIX
a
•
FVIIIa
FX
Free protein S
APC
FXa
•
FVa
Prothrombin
(II)
Thrombin
(IIa)
Protein C
Ca2
+
Thrombomodulin
Endothelium
•
Endothelial
Protein C
Receptor
Figure shows the anticoagulant
mechanisms of the protein C–
protein S system
Factor V (FV) is a clotting factor
with activity regulated by the
anti-coagulant activated Protein C
(APC)
FV is one of many components of
the clotting cascade, which is
ideally in homeostasis so as to
prevent a bleeding disorder e.g.
thrombophilia
What is factor V Leiden (FVL)?
• The mutation (Leiden) in the
FIX
a
FVIIIa
FX
Free protein S
APC
FXa
FVa
Prothrombin
(II)
Endothelium
Thrombin
Thrombin
(IIa)
Thrombin
Thrombin
Ca2
(IIa)
+
Thrombin
Thrombin
(IIa)
(IIa)
(IIa)
(IIa)
Thrombomodulin
Protein C
Endothelial
Protein C
Receptor
factor V (FV) gene results in
FV being inactivated more
slowly by APC, generating
more thrombin and thus
increasing the potential for
thrombosis
• Some individuals may inherit
more than one risk factor,
i.e. FVL and prothrombin
mutations are seen in
1/1000 individuals
Approach to Hemostatic Disorders:
Clinical and Laboratory Approach
What is the diagnosis?
Clinical Evaluation of Bleeding Patients
“80% of correct diagnosis can be made by history taking
and physical examination.”
History Taking
• Identify if the bleeding problem is due to
• Local vs. systemic defect
• Location: single vs. multiple sites
• Severity: Spontaneous? Appropriate to trauma?
• Hereditary vs. acquired disorder
• Onset
• Family history
• Underlying disease
• Medication
• Primary vs. secondary hemostatic disoder
Onset
Primary Hemostasis
Secondary Hemostasis
Immediate
Delayed
Sites
Skin
Superficial
Petechiae, superficial
ecchymosis
Deep
Deep ecchymosis,
hematoma
Mucosal
Common
Rare
Others
Rare
Retroperitoneal
hematoma, hemarthrosis
Primary Hemostatic defect
Secondary Hemostatic defect
Platelet
Petechiae, Purpura
Coagulation
Hematoma
Assessment of Primary Hemostasis
• Platelet
• Complete blood count (CBC)
• Bleeding time/ PFA-100
• Platelet aggregation study
• Blood vessel
• Bleeding time
• von Willebrand factor (vWF)
• Bleeding time
• vWF Antigen, vWF: RCO, vWF multimer, FVIII
Complete Blood Count (CBC)
• Platelet number
• Normal platelet count: 150,000 –400,000/uL
• > 100,000/uL
Bleeding unlikely
• < 20,000/uL
↑ risk for spontaneous
•
bleeding
• Must exclude pseudothrombocytopenia
• Assess for platelet morphology
Causes of Thrombocytopenia
• Production failure
• Isolated thrombocytopenia
• Pancytopenia
• Increased peripheral destruction
• immune
• non-immune
• Splenic pooling (sequestration)
• Hypersplenism
• Dilutional
• Massive blood transfusion
Peripheral destruction: immune thrombocytopenia
• Autoimmue
• ITP
• acute
• chronic
• Alloimmune
• Neonatal alloimmune thrombocytopenia
• Post-transfusion purpura
Bleeding Time
Bleeding Time: Interpretation
• Normal value* : 1-9 min
• Prolonged bleeding time:
• Thrombocytopenia/ anemia (Hct < 20%)
• Hereditary platelet dysfunction
• von Willebrand disease
• Severe hypofibrinogenemia
• Blood vessels disorders
• Uremia
• Myeloproliferative disorders
• Medication: Aspirin, NSAIDs,other antiplatelet drugs
Approach to platelet disorders
• Low platelet count
• Bone marrow
examination
• Platelet antibodies
• Screening tests for DIC
• Normal platelet count
• Bleeding time
• Platelet aggregation
study
• von Willebrand disease
study
Primary Hemostasis: vWF
Arterioscler Thromb Vasc Biol 2000 20:285
Von Willebrand Disease
• Defect of Von Willebrand Factor
• quantitative
• qualitative
• Autosomal dominant
• Normal function of VWF
• Mediate platelet adhesion
• Stabilize factor VIII in circulation
• Localize factor VIII to site of vessel injury
Von Willebrand Disease
• Pattern of bleeding
• Usually platelet type
• Coagulation type if severe
• Diagnostic tests
• Factor VIII activity
• VWF antigen assay
• VWF function, e.g. ristocetin cofactor assay
Platelet aggregation
• Platelets function in primary hemeostasis by forming an
initial platelet plug at the site of vascular injury. The
phenomenon occurs partly through the ability of platelets
to adhere to one another, a process known as platelet
aggregation.
• Substances that can induce platelet aggregation include;
Collagen, ADP, epinephrine, thrombin, serotonin,
arachidonic acid, restocetin, snake venoms. Platelet
aggregation is an essential part of the investigation of any
patient with a suspected platelet dysfunction. Platelet
aggregation is studied by means a platelet aggregometer.
Assessment of Secondary Hemostasis
• Screening tests:
• PT
• aPTT
• Mixing study
• Additional Tests
• Fibrinogen
• Thrombin Time
• Coagulation factor
assays
• D-dimer
• Fibrin Degradation
Product
Prothrombin Time (PT)
PT : test extrinsic and common pathway
Activated Partial Thromboplastin Time (aPTT)
aPTT : test intrinsic and common pathway
Mixing Study
Deficiency
Correctable
Normal
coagulation time
50%
+
Inhibitor
0%
prolonged
coagulation time
100%
Prolonged PT or aPTT occurs when
coagulation factor < 35-40%
Uncorrectable
<35%
Interpretation of Abnormal Coagulogram
• Isolated prolonged PT
• Isolated prolonaged aPTT
• Prolonged PT and aPTT
Acquired FVIII inhibitor
Further Diagnostic Tests
• Specific coagulation factor assay
• Coagulation factor inhibitor assay
• Lupus anticoagulant panel
Other Tests for Secondary Hemostasis
• Fibrinogen
• D-dimer
• Fibrin(ogen) degradtion product
• Thrombin time
Fibrinogen
• Functional level (200-400 mg/dl)
• ↓ Fibrinogen
(esp. < 100 )
•
•
•
•
•
DIC
Fibrinolytic therapy
Primary fibrinolytic state
Congenital afibrinogenemia
Acquired/congenital dysfibrinogenemia
• ↑ Fibrinogen
• Inflammatory states/acute illness
• May associated with shortened PT/aPTT
D-Dimer
• Measured cross-linked fibrin degradation product by
plasmin
• More sensitive and specific for fibrinolysis than
Fibrin(ogen) Degradatioin Product (FDP)
• ↑ D-dimer:
• DIC
• Acute thromboembolic episodes
• Post-trauma or surgery
• Malignancy
Fibrin(ogen) Degradation Product
• ↑ levels in
• Primary fibrinolytic syndromes
• DIC
• After lytic therapy
• Acute thromboembolic episodes
• After injury/surgery
Thrombin Time
• Thrombin Time (TT)
• Assess the ability to convert fibrinogen  fibrin by adding
thrombin to plasma
• Prolonged TT:
• Inhibitor of thrombin: heparin, anti-thrombin antibody
• Hypofibrinogenemia or dysfibrinogenemia
• Inhibitor of fibrin polymerization: fibrin degradation product,
paraprotein
IDIOPATHIC THROMBOCYTOPENIA PURPURA (ITP)
• Acute - children (post infection)
• Chronic - adults ( females,20-40 yrs)
• IgG autoantibodies bound to platelets
• Platelets removed by macrophages
• Antibodies can act on marrow
• No good diagnostic test
• Treatment - Inhibit macrophage clearance
• Corticosteroids
• High dose gamma globulin
• Splenectomy
Coagulation disorders:
• Deficiencies of Clotting factors
• Onset - delayed after trauma
• Deep bleeding
• Into joints - Hemarthroses
• Into deep tissues – Hematoma
• large skin bleed – Ecchymoses
Coagulation Disorders
• Normal bleeding time & Platelet count
• Prolonged prothrombin time (PT)
• deficiencies of II, V, VII, X
• Prolonged time (aPTT)
• all factors except VII, XIII
• Mixing studies - normal plasma corrects PT or aPTT
Factor VIII Deficiency
• X-linked disorder (affects 1º males)
• Prevalence is 1:5,000 males
• Most common - severe bleeding
• Spontaneous hematomas
• Abnormal aPTT – Intrinsic path.
• Diagnosis - factor VIII assay
• Treatment - factor VIII concentrate
Factor IX Deficiency
• X-linked recessive disorder
• Prevalence is 1:30,000 males
• Indistinguishable from classic hemophilia (F VIII)
• Requires evaluation of factor VIII and IX activity
levels to diagnose
• Treatment - factor IX concentrate
FACTOR XI DEFICENCY
• Inherited form transmitted as an autosomal recessive
trait.
• Prevalence is 1:100,000
• Increased prevalence in Ashkenazi Jewish population
• A clinically mild bleeding problem
• Prolongs only the PTT
• Most often associated with liver disease
Secondary Hemostatic Disorders
• Neonates - decreased intestinal
flora and dietary intake
• Oral anticoagulants (coumadin)
• Fat malabsorption syndromes
• Required for factors II, VII, IX, - Prolonged PT and
aPTT
Combined Primary and Secondary Hemostatic
Disorders
Disseminated Intravascular Coagulation (DIC)
• Major pathologic processes -
obstetric complications, neoplasms, infection (sepsis),
major trauma
• Primary - platelet consumption
( bleeding time,  platelets)
• Secondary - factor consumption
( PT, aPTT)
Combined Primary and Secondary Hemostatic
Disorders; Severe Liver Disease
• Primary - dysfunctional platelets and/or thrombocytopenia
(BT)
• Secondary - decrease in all coagulation factors except
vWF (PT, aPTT)
• Vitamin K will promote synthesis of factors II, VII, IX, X
THROMBOPHILIA—
HYPERCOAGULABLE
STATES
Risk Factors for Thrombosis
Hereditary
thrombophilia
Immobility
Atherosclerosis
Thrombosis
Acquired
thrombophilia
Surgery
trauma
Estrogens
Inflammation
Malignancy
Risk Factors—Inherited
• Antithrombin deficiency
• Protein C deficiency
• Protein S deficiency
• Factor V Leiden mutation (Factor V-Arg506Gln)
• Prothrombin gene mutation (G A transition at position
20210)
• Dysfibrinogenemias (rare)
Antiphospholipid Syndrome—Diagnosis
• Clinical Criteria
-Arterial or venous thrombosis
-Pregnancy morbidity
• Laboratory Criteria
-IgG or IgM anticardiolipin antibody
-Lupus Anticoagulant
Site of Thrombosis vs. Coag. Defect
Abnormality
Arterial
Factor V Leiden
Prothrombin G20210A
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
Hyperhomocysteinemia
Lupus Anticoagulant
Venous
+
+
+
+
+
+
+
+
+
CALCIUM AND
PHOSPHATE BALANCE
DR. MALIK ALQUB MD. PHD.
INTRODUCTION
• The maintenance of calcium and phosphate homeostasis
involves changes in intestinal, bone, and renal function.
Regulation of intestinal function is important because, in
contrast to the complete absorption of dietary NaCl and
KCl, the absorption of Ca2+ and phosphate is incomplete.
This limitation is due both to the requirement for vitamin
D and to the formation of insoluble salts in the intestinal
lumen, such as calcium phosphate, calcium oxalate, and
magnesium phosphate.
INTRODUCTION
• Most of the body Ca2+ and much of the phosphate exist
as hydroxyapatite, Ca10(PO4)6(OH)2, the main mineral
component of bone. Phosphate also is present in high
concentration in the cells. Within the plasma, both Ca2+
and phosphate circulate in different forms. Of the plasma
Ca2+, roughly 40 percent is bound to albumin, 10 percent
is complexed with citrate, sulfate, or phosphate, and 50
percent exists as the physiologically important ionized (or
free) Ca2+.
Three Forms of Circulating Ca2+
Calcium Balance
PARATHYROID HORMONE
• Parathyroid hormone (PTH) is a polypeptide secreted
from the parathyroid glands in response to a decrease in
the plasma concentration of ionized Ca2+ . This change is
sensed by a specific Ca2+-sensing protein in the cell
membrane of the parathyroid cells. The receptor permits
variations in the plasma Ca2+ concentration to be sensed
by the parathyroid gland, leading to the desired changes
in PTH secretion.
Regulation of PTH Secretion and
Biosynthesis
• Extracellular Ca 2+ regulates secretion of PTH
• Low Ca 2+ increases
• High Ca 2+ decreases
• Ca2+ also regulates transcription
• High levels of 1,25 dihydroxyvitamin D3 inhibit
transcription
PARATHYROID glands
PARATHYROID HORMONE
PTH acts to increase the plasma Ca2+ concentration in
three ways:
• In the presence of permissive amounts of vitamin D, it
stimulates bone resorption, resulting in the release of
calcium phosphate.
• It enhances intestinal Ca2+ and phosphate absorption by
promoting the formation within the kidney of
calcitriol (1,25 dihydroxycholecalciferol), the major active
metabolite of vitamin D.
• It augments active renal Ca2+ reabsorption.
PARATHYROID HORMONE
PTH also influences phosphate balance, although its
actions.
• It tends to increase phosphate entry into the extracellular
fluid by its effects on bone and intestinal absorption.
• PTH also reduces proximal tubular phosphate
reabsorption, resulting in enhanced excretion.
VITAMIN D
• is a fat-soluble steroid, which is present in the diet and
also can be synthesized in the skin from 7dehydrocholesterol in the presence of ultraviolet light. The
hepatic enzyme 25–hydroxylase places a hydroxyl group
in the 25 position of the vitamin D molecule, resulting in
the formation of 25-hydroxyvitamin D or calcidiol.
VITAMIN D
• Calcidiol produced by the liver enters the circulation and
travels to the kidney, bound to vitamin D binding protein.
In the kidney, tubular cells contain two enzymes (1-alphahydroxylase and 24-alpha-hydroxylase) that can further
hydroxylate calcidiol, producing 1,25 dihydroxyvitamin D
(calcitriol), the most active form of vitamin D.
VITAMIN D
• The main action of calcitriol is to enhance the availability
of calcium and phosphate both for new bone formation
and for the prevention of symptomatic hypocalcemia and
hypophosphatemia. This is primarily achieved by
increases in bone resorption, intestinal absorption, and
renal tubular Ca2+ reabsorption;
REGULATION OF PLASMA CALCIUM
AND PHOSPHATE CONCENTRATIONS
• for example, hypocalcemia does occur, there is a direct
stimulus to PTH secretion and the subsequent formation
of calcitriol. PTH increases calcium phosphate release
from bone and urinary phosphate excretion, whereas
calcitriol augments intestinal calcium phosphate
absorption. Both hormones also reduce urinary Ca2+
excretion. The net effect is an increase in the plasma
Ca2+ concentration with little change in the plasma
phosphate concentration. This sequence is reversed with
hypercalcemia or a high Ca2+ diet as both PTH secretion
and calcitriol production are diminished.
Calcitonin
• Product of parafollicular C
cells of the thyroid
• 32 aa
• Inhibits osteoclast mediated
bone resorption
• This decreases serum Ca2+
• Promotes renal excretion of
Ca2+
Calcitonin
• Probably not essential for human survival
• Potential treatment for hypercalcemia
• In humans, even extreme variations in calcitonin production do
not change calcium and phosphate metabolism; no definite
effects are attributable to calcitonin deficiency (totally
thyroidectomized patients receiving only replacement
thyroxine) or excess (patients with medullary carcinoma of the
thyroid, a calcitoninsecreting tumor). Calcitonin has been a
useful pharmacologic agent to suppress bone resorption in
Paget’s disease and osteoporosis and in the treatment of
hypercalcemia of malignancy. However, bisphosphonates are
usually more effective, and the physiologic role, if any, of
calcitonin in humans is uncertain.
Measuring the total plasma Ca2+
• Measuring the total plasma Ca2+ concentration is
sufficient, since changes in this parameter usually are
associated with parallel changes in the ionized
concentration.
Three Forms of Circulating Ca2+
Different Forms of Calcium
At any one time, most of the calcium in the body exists as the
mineral hydroxyapatite, Ca10(PO4)6(OH)2.
Calcium in the plasma:
45% in ionized form (the physiologically active form)
45% bound to proteins (predominantly albumin)
10% complexed with anions (citrate, sulfate, phosphate)
To estimate the physiologic levels of ionized calcium in states
of hypoalbuminemia:
[Ca+2]Corrected = [Ca+2]Measured + [ 0.8 (4 – Albumin) ]
Hypercalcemia: History
• ● Malignancy
• ● Constitutional symptoms
• ● Medication use (thiazides, lithium)
• ● Family history
Hypercalcemia: Signs and Symptoms
• Constipation
• Abdominal pain
• Decreased mentation
• Lassitude
• Nocturia
• Polyuria
• Volume depletion
• Flank pain: Kidney stones
• Peptic ulcer disease
Etiologies of Hypercalcemia
• By prevalence:
• ● Primary hyperparathyroidism (55%)
• ● Malignancy (35%)
• Humoral hypercalcemia of malignancy: PTHrp, usually lung,
esophagus, head and neck, renal cell, ovary bladder
• Local osteolytic hypercalcemia, including:
• Breast and multiple myeloma
• Hematologic malignancy (lymphoma) with ectopic production of
1,25-dihydroxyvitamin D
• ● All other causes (10%) including drugs
• (thiazides, lithium, vitamin D), immobilization,
pheochromocytoma, thyrotoxicosis, milk-alkali
Diagnostic Tests
• Ca, PTH, 25(OH)D and 1,25(OH)2D levels, PTHrp
HYPOCALCEMIA: History
• Previous thyroid, parathyroid, or neck surgery
• Chronic kidney disease
• Diarrhea
• Previous bowel surgery
• Lack of sunlight
• Low dietary Ca and vitamin D
HYPOCALCEMIA: Signs and Symptoms
• ● Neck scar
• ● Positive Chvostek’s, positive Trousseau’s signs
• ● Perioral numbness
• ● Tetany
• ● Dyspnea
• ● Stridor
• ● Wheezing
• ● Seizures
• ● Bone pain
• ● Muscle weakness
Etiologies of HYPOCALCEMIA
• The causes of hypocalcemia can be divided into those in which
• PTH is absent (hereditary or acquired hypoparathyroidism,
•
•
•
•
hypomagnesemia),
PTH is ineffective (chronic renal failure, vitamin D deficiency,
anticonvulsant therapy, intestinal malabsorption,
pseudohypoparathyroidism),
PTH is overwhelmed (severe, acute hyperphosphatemia in
tumor lysis, acute renal failure, or rhabdomyolysis; hungry bone
syndrome following parathyroidectomy).
The most common forms of chronic severe hypocalcemia are
autoimmune hypoparathyroidism and postoperative following
neck surgery. Chronic renal insufficiency is
ashypoparathyroidism sociated with mild hypocalcemia
compensated for by secondary hyperparathyroidism. The
cause of hypocalcemia associated with acute pancreatitis
is unclear.
Etiologies of HYPOCALCEMIA
• Low albumin (correct Ca level for albumin to make sure
•
•
•
•
•
•
•
true hypocalcemia)
Hypoparathyroidism: postsurgical, postradiation,
congenital, autoimmune
Vitamin D deficiency: renal failure, poor nutrition,
malabsorption, short bowel, cirrhosis
Pancreatitis
Pseudohypoparathyroidism
Hypomagnesemia
Increased phosphate (binds more Ca): rhabdomyolysis,
tumor lysis syndrome, kidney failure
Hungry bone syndrome
Diagnostic Tests
• Ca, albumin, Mg, P, PTH, 25(OH)D, and 1,25(OH)2D
levels
HYPOPHOSPHATEMIA: history
• Observed in 10% of hospitalized alcoholics
• Gastrointestinal disorders, diarrhea, recent severe illness,
•
•
•
•
weight change
Diabetic ketoacidosis
Critical illness/ventilated: Observed in 3% of all
hospitalized patients, up to 70% of intensive-care-unit
patients
On total parenteral nutrition
renal transplant
HYPOPHOSPHATEMIA: Symptoms
• Muscle weakness
• Hypoventilation
• Confusion
• Seizures
• Osteomalacia
Differential Diagnosis
• Decreased GI Absorption
• Phosphate binders (calcium acetate)
•
• Decreased Bone Resorption / Increased Bone
Mineralization
• Vitamin D deficiency / low calcitriol
• Increased Urinary Excretion
• Elevated PTH (as in primary hyperparathyroidism)
• Vitamin D deficiency / low calcitriol
HYPERPHOSPHATEMIA: history
• Renal failure
• Tumor lysis syndrome
• Rhabdomyolysis
HYPERPHOSPHATEMIA: Symptoms
• Asymptomatic unless hypocalcemia occurs due to
precipitation of insoluble Ca-P complexes and decreased
calcitriol synthesis
• Chronic hyperphosphatemia in renal failure is associated
with vascular calcification and increased mortality
Diagnostic Tests
• Serum P and creatinine/glomerular filtration rate
Hyperparathyroidism
• The disorder is characterized by hypercalcemia,
hypercalcuria, hypophosphatemia, and
hyperphosphaturia
• Parathyroid hormone causes phosphaturia and a
decrease in serum phosphate
• Calcium rises and it is also secreted in the urine
• Most common complication are renal stones made
of calcium phosphate
• Most serious complication is the deposition of
calcium in the kidney tubules resulting in impaired
renal function
Hyperparathyroidism Clinical Sx
• Kidney stones, painful bones, abdominal groans,
psychic moans, and fatigue overtones
• Kidney stones calcium phosphate and oxalate
• Osteopenia, osteoporosis.
• Peptic ulcer disease, pancreatitis
• Psychiatric manifestations such as psychosis,
coma, depression, anxiety, fatigue
Pathophysiology
• Primary
• Adenoma
• Hyperplasia
• Carcinoma
• Secondary
• Hyperplasia
• chronic renal failure, malabsorbtion
Magnesium (Mg)
• Total body Mg approximates 25g; it is the fourth most
abundant cation extracellularly, and the second most
abundant cation intracellularly. Bone contains about 60%
of total body Mg. The normal serum Mg is 1.7-2.1 mg/dl.
Serum Mg is quite constant but the mechanism of its
regulation is not well known. The kidney is the major
organ controlling Mg excretion. Renal excretion is quite
sensitive to Mg depletion and ranges from 2- 10% of the
filtered load. Magnesium deficiency can cause
neuromuscular hyperexcitability. Chronic Mg depletion is
accompanied by hypocalcemia due to partial inhibition of
PTH secretion and a blunted skeletal response to PTH.
HYPERMAGNESEMIA
• Differential Diagnosis
• (Occurs almost exclusively with chronic kidney disease)
• Increased intake: Antacids, laxatives, enemas, or
treatment of preeclampsia with Mg salts
• Diagnostic Tests
• Mg, creatinine
HYPERMAGNESEMIA
• Hypermagnesemia is rare but can be seen in renal failure
when pts are taking magnesium-containing antacids,
laxatives, enemas, or infusions, or in acute
rhabdomyolysis. The most readily detectable clinical sign
of hypermagnesemia is the disappearance of deep
tendon reflexes, but hypocalcemia, hypotension, paralysis
of respiratory muscles, complete heart block, and cardiac
arrest can occur.
HYPOMAGNESEMIA
• Hypomagnesemia usually indicates significant whole body
magnesium depletion. Muscle weakness, prolonged PR
and QT intervals, and cardiac arrhythmias are the most
common manifestations of hypomagnesemia. Magnesium
is important for effective PTH secretion as well as the
renal and skeletal responsiveness to PTH. Therefore,
hypomagnesemia is often associated with hypocalcemia.
HYPOMAGNESEMIA
• History
• Alcohol use
• Diarrhea/malabsorption
• Medications (cisplatin, aminoglycosides, amphotericin,
loop diuretics, digoxin)
• Signs and Symptoms
• Tremor of extremities and tongue, myoclonic jerks,
Chvostek sign, Trousseau sign, tetany, general muscular
weakness (particularly
• respiratory muscles), coma, vertigo, nystagmus,
movement disorders
LIVER FUNCTION TEST
Dr. Malik ALQUB
Liver dysfunction diagnosis
• The diagnosis of liver disease depends on a combination of
patient history, physical examination, laboratory testing,
biopsy and sometimes imaging studies such as ultrasound
scans.
CLINICAL HISTORY
• The clinical history should focus on the symptoms of liver
disease—their nature, patterns of onset, and
progression—and on potential risk factors for liver
disease.
The manifestations of liver disease
• constitutional symptoms such as fatigue, weakness,
nausea, poor appetite, and malaise
• more liver-specific symptoms of jaundice, dark urine, light
stools, itching, abdominal pain, and bloating.
• Fatigue is the most common and most characteristic
symptom of liver disease. It is variously described as
lethargy, weakness, listlessness, malaise, increased need
for sleep, and poor energy.
• The fatigue of liver disease typically arises after activity or
exercise and is rarely present or severe after adequate
rest; i.e., it is “afternoon” rather than “morning” fatigue.
The manifestations of liver disease
• Nausea occurs with more severe liver disease and may
accompany fatigue or be provoked by smelling food odors
or eating fatty foods.
• Right-upper-quadrant discomfort or ache (“liver pain”)
occurs in many liver diseases and is usually marked by
tenderness over the liver area.
• Itching occurs with acute liver disease, appearing early in
obstructive jaundice
• Jaundice is the hallmark symptom of liver disease and
perhaps the most reliable marker of severity.
Major risk factors for liver disease
• Family Hx
• Hemochromatosis, Wilson’s Disease, alpha1 antitrypsin
deficiency
• Gilbert’s syndrome, Dubin-Johnson Syndrome, Rotor’s
syndrome
• Sexual History
• Tattoos
• Travel history
• recent surgery
• remote or recent transfusion of blood or blood
products
• accidental exposure to blood or needlestick
Major risk factors for liver disease
• Occupational exposures
• Chemicals (vinyl choloride, dimethylformamide, 2Nitropropane, Trichloroethylene)
• Other co-morbid illnesses
• Autoimmune diseases, IBD, Diabetes Mellitus
• Medications
• Prescription
• Herbals, Vitamins
Medications causing elevation of
aminotransferases
• Acetaminophen
• Amoxicillin-clavulanic acid
• HMGCoA reductase inhbtrs
• NSAIDS
• Phenytoin
• Valproate
PHYSICAL EXAMINATION
• Typical physical findings in liver disease are icterus,
hepatomegaly, hepatic tenderness, splenomegaly, spider
angiomata, palmar erythema, and excoriations. Signs of
advanced disease include muscle wasting, ascites,
edema, dilated abdominal veins, hepatic fetor, asterixis,
mental confusion, stupor, and coma. In male patients with
cirrhosis, particularly that related to alcohol use, signs of
hyperestrogenemia such as gynecomastia, testicular
atrophy, and loss of male-pattern hair distribution may be
found.
physical findings in liver disease
• icterus
• spider angiomata
physical findings in liver disease
• palmar erythema
• palmar erythema
physical findings in liver disease
• Fingure clubbing
Caput medusae
• gynecomastia
Liver Function Test: Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
Common serum liver chemistry tests
Normal values
ALT (SGPT) and AST (SGOT) levels
• AST and ALT are markers of hepatocellular injury
• Participate in gluconeogenesis, transfer of amino
groups from aspartate or alanine to ketoglutaric
acid to form oxaloacetete or pyruvate.
• AST present in cytosol and mitochondria in liver,
cardiac muscle, skeletal muscle, kidney, brain,
pancreas, lungs, WBC and RBC.
• ALT a cytosolic enzyme, highest concentration in
the liver
• ALT considered a “liver specific” enzyme
Aminotransferases
• Hepatic enzymes that are usually intracellular, but are
released from hepatocytes with hepatocellular injury.
• Includes aspartate aminotransferase (AST) and alanine
aminotransferase (ALT)
• AST/ALT ratio
• Normal is 0.8
• In alcoholic hepatitis, is usually > 2
Isolated elevated AST
• If ALT normal, then reflective of cardiac or
muscle disease.
• Marco-AST
• Rare
• AST complexed with an immunoglobulin and is not
cleared from the blood
• Does not indicate serious liver disease
• Drugs
• Acetominophen, NSAIDs, ACE-I, Niacin,
Erythromycin, Fluconazole
Useful paradigm to categorize increased levels of AST,
ALT
• Mild AST, ALT elevation (less than 5 times ULN) - ALT
predominant or AST predominant
• AST, ALT greater than 15 times normal
AGA Technical review, Gastroenterology 2002
Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
Alkaline phosphatase
•Present in nearly all tissues - isoenzymes
•Localised in the microvilli of the bile canalicus
in the liver
•Also present in bone, intestine, placenta,
kidney and wbc
•Elevation may be physiological or pathological
•Normal adult serum AP is from liver and bone
Intestine contributes about 15%
Elevation of s. alkaline phosphatase
• Isolated
• Associated with hyperbilirubinemia (cholestatic disorders)
• May be sole abnormality in many cholestatic or infiltrative
diseases
• To be interpreted in the clinical setting of history and
physical examination if sole abnormality
GGT
• Catalyzes the transfer of the γ-glutamyl group
from γ-glutamyl peptides (glutathione) to other
peptides and L-amino acids.
• Elevated in liver, biliary, or pancreatic disease.
• Very sensitive for detecting hepatobiliary disease,
but poor specificity
• Used primarily to confirm hepatic origin of
elevated ALP
Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
• Bilirubin
• Albumin
• PT
Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
• Bilirubin
• Albumin
• PT
Bilirubin Metabolism
Bilirubin Metabolism: Pre-Hepatic





Bilirubin is formed in macrophages of the reticuloendothelial
system. The initial substrate is predominantly hemaglobin.
Heme group  biliverdin  bilirubin
Bilirubin is insoluble in water and so must be carried by
albumin within plasma.
Bilirubin circulates in the blood before uptake by the liver.
Pre-hepatic jaundice = if bilirubin is not taken up by the liver
or if it is produced in excess, unconjugated bilirubin is
deposited in extra-hepatic tissues.
Bilirubin Metabolism: Hepatic
• Bilirubin is taken up into hepatocytes and bound to
intracellular proteins.
• Bilirubin + UDP glucuronic acid = bilirubin diglucuronide
> bilirubin monoglucuronide > UDP
• The glucuronide conjugated form of bilirubin is water
soluble and is excreted into bile. Excretion occurs into
the bile canaliculus by carrier-mediated transport.
• Hepatic jaundice = disorders of bilirubin uptake or
conjugation
Bilirubin Metabolism: Post-Hepatic
• Glucuronide-conjugated bilirubin in bile may be degraded to
urobilinogen or partially reabsorbed into plasma.
• Urobilinogen pathway:
• may be reabsorbed by the gut and returned to the liver
• converted to urobilin
• reabsorbed into plasma for excretion by kidneys
• Conjugated bilirubin pathway:
• May be acted upon by bacterial enzymes within the gut to form
the bile pigment stercobilinogen. Stercobilinogen may be
reabsorbed into plasma for recycling to the liver or for excretion
by the kidney, or, it may be oxidized to stercobilin.
• Obstructive jaundice = failure of bilirubin to reach the gut,
resulting in a reduction in pigment within the stool
Hyperbilirubinemia
• Pre-hepatic
• Hepatic
• Post-hepatic
Pre-hepatic
• The human body produces about 4 mg per kg of bilirubin
per day from the metabolism of heme. Approximately 80
percent of the heme moiety comes from catabolism of red
blood cells, with the remaining 20 percent resulting from
ineffective erythropoiesis and breakdown of muscle
myoglobin and cytochromes. Bilirubin is transported from
the plasma to the liver for conjugation and excretion.
Hepatic
• Intrahepatic Causes of Conjugated Hyperbilirubinemia
• Hepatocellular disease
• Viral infections (hepatitis A, B, and C)
• Chronic alcohol use
• Autoimmune disorders
• Drugs
• Pregnancy
• Parenteral nutrition
• Sarcoidosis
• Dubin-Johnson syndrome
• Rotor’s syndrome
• Primary biliary cirrhosis
• Primary sclerosing cholangitis
Post-hepatic
• Extrahepatic Causes of Conjugated Hyperbilirubinemia
• Intrinsic to the ductal system
• Gallstones
• Surgical strictures
• Infection (cytomegalovirus, Cryptosporidium
• infection in patients with acquired immunodeficiency syndrome)
• Intrahepatic malignancy
• Cholangiocarcinoma
• Extrinsic to the ductal system
• Extrahepatic malignancy (pancreas, lymphoma)
• Pancreatitis
DDX: Unconjugated Hyperbilirubinemia



Increased Bilirubin Production
 Extravascular hemolysis
 Extravasation of blood into tissues
 Intravascular hemolysis
 Errors in production of red blood cells
Impaired Hepatic Bilirubin Uptake
 CHF
 Portosystemic shunts
 Drug inhibition: rifampin, probenecid
Impaired Bilirubin Conjugation
 Gilbert’s disease
 Crigler-Najarr syndrome
 Neonatal jaundice (this is physiologic)
 Hyperthyroidism
 Estrogens
 Liver diseases (chronic hepatitis, cirrhosis, Wilson’s)
DDX: Conjugated Hyperbilirubinemia

Intrahepatic Cholestasis (impaired excretion)
 Hepatitis (viral, alcoholic, and non-alcoholic)
 Primary biliary cirrhosis or end-stage liver dz
 Sepsis and hypoperfusion states
 Pregnancy
 Infiltrative disease: TB, amyloid, sarcoid, lymphoma
 Drugs/toxins i.e. chlorpromazine, arsenic
 Post-op patient or post-organ transplantation
 Hepatic crisis in sickle cell disease
Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
• Bilirubin
• Albumin
• PT
Albumin
• Synthesized exclusively by the liver
• 20 day half life - levels usually preserved
acutely
• Synthesis regulated by nutritional states,
osmotic pressure, systemic inflammation, and
hormones
• Hypoalbuminemia most common in patients
with chronic liver disorders (ie cirrhosis) due to
decreased synthesis
• Not specific for liver disease
Three categories
• Markers of Liver Injury/Necrosis
• Markers of Cholestatic Liver Disease
• Markers of Liver Function
• Bilirubin
• Albumin
• PT
Prothrombin Time
• Factor 1 - fibrinogen
• Factor II- prothrombin
• Factor V - proaccelerin; labile factor
• Factor VII - stable factor
• Factor IX - Christmas factor
• Factor X - Stuart Prower factor
• Factor XII and XIII - prekallikrein and high
molecular weight kinogen
Prothrombin Time
• Parenchymal liver disease
• Poor utilization of vitamin K
• Hypovitaminosis K
• Prolonged obstructive Jaundice
• Steatorrhea
• Dietary Deficiency
• Antibiotics (alter gut flora)
• Differentiate by giving IV Vitamin K
• normalization or 30% improvement within 24 hrs
surmises good parenchymal function
Platelets
• Thrombocytopenia seen in liver is thought to
be due to congestive splenomegaly
• Mechanism is platelet sequestration
• Correlation shown between spleen size and
thrombocytopenia
• Platelet count rarely less than 50K
• Bleeding associated with it uncommon
• Congestive splenomegaly does not induce a
significant hemostatic defect
Assessing the patient with abnormal Liver
Function Tests
• Most of the time, the cause of elevated LFTs can be
elicited without invasive testing (biopsy)
• If no cause of abnormality is found, most frequently
the cause is alcohol liver disease, steatosis, or
steatohepatitis
• Certain patterns exist with LFTs
• Hepatocellular Injury: Very high AST, ALT with
mild/moderately elevated alkaline phosphatase.
• Cholestatis: mild/moderately elevated AST/ALT with very
high alkaline phosphatase
• Bilirubin can be elevated with both combinations.
Hepatocellular Injury
• Medications:
• History: Need to assess temporal relationship with drug, see if
patient improves once medication removed
• NSAIDs, antibiotics, statins, anti-tuberculosis medications,
anti-epileptic drugs, acetaminophen
• Frequently cause isolated elevated aminotransferases
• Acetaminophen overdose
• Toxicity is likely to occur with single ingestions greater than 250 mg/kg or
those greater than 12 g over a 24-hour period
• AST/ALT elevations is first sign of liver damage (usually 24-hours after
ingestion)
• Alcohol Use:
• Frequently have AST:ALT ratio ≥ 2:1
• History: Need accurate assessment of alcohol intake, including
CAGE questions.
Hepatocellular Injury
• Hepatitis A:
• Acute infection
• History: travel, recent outbreak, MSM; nausea, vomiting, jaundice
• Labs: Hepatitis A IgM, frequent elevated bilirubin
• Hepatitis B:
• Can be acute or chronic
• History: See if patient from Asia, Subsaharan Africa; Sexual history, Drug use
• Labs: Hepatitis B surface antigen, surface antibody, core antibody
• Hepatitis C:
• History: IV drug abuse, blood transfusion prior to 1992, Sexual history, Tattoos
• Labs: Hepatitis C antibody (Hepatitis C viral load if HIV positive or immunocompromised)
• HIV:
• Often causes isolated elevated aminotransferases
• History: Sexual History, IV drug use
• Labs: HIV Antibody test
Hepatocellular Injury
• Hereditary Hemochromatosis
• History: Family history of liver disease? Diabetes? Heart Failure?
Bronze skin?
• Labs:
• Serum iron, TIBC
• Ferritin
• If > 400 ng/mL in men, or > 300 ng/mL in women, then need to check liver
biopsy or genetic testing
Hepatocellular Injury
• Hepatic steatosis/Non-alcoholic
steatohepatitis (NASH)
• Increase in AST/ALT are usually less than 4-fold.
• History: Female, obesity, diabetes
• Labs:
• Labs to rule out other causes of hepatitis
• Abdominal Ultrasound: look for fatty infiltration of liver
Hepatocellular Injury
• Autoimmune Hepatitis
• History: Young to middle-aged female
• Labs:
• Anti-nucleur antibody: Positive
• Anti-smooth-muscle antibody (SMA)
• Liver biopsy: should be performed if the above are negative, but
autoimmune hepatitis still suspected.
Hepatocellular Injury
• Alpha-1-antitrypsin deficiency
• History: Family history, emphysema,
young age
• Labs:
• Alpha-1-antitrypsin level/phenotype
Hepatocellular Injury
• Wilson’s Disease
• A genetic disorder of biliary copper excretion
• History: Age (usually age 5 – 25, but up to age 40), family
history of liver disease; neuropsychiatric disease
• Evaluation:
•
•
•
•
Serum ceruloplasmin: Low
Opthalmologist: Exam for Kayser-Fleisher rings
24-hour urine copper
Liver biopsy: Evaluate liver copper levels
Wilson’s Disease – Kayser-Fleisher Rings
Hepatocellular Injury
• Shock Liver (ischemic hepatitis)
• Etiology: Shock, severe hypotension
• Severely elevated AST/ALT (50 times normal)
Hepatocellular Injury
• What if work-up is negative and AST/ALT remain
elevated?
• Observe:
• Patients with two-fold or less increase in AST/ALT and no
hyperbilirubinemia
• Liver Biopsy
• Patients with > two-fold increase in AST/ALT, or abnormalities of other
liver function tests.
Cholestatic Pattern - Intrahepatic
• Primary Biliary Cirrhosis
• Autoimmune disease
• Predominately in women, usually ages 35-65
• May have history of other autoimmune disease
• Symptoms: Prurutis, fatigue, hyperpigmentation,
musculoskeletal complaints
• Labs:
• Anti-mitochondrial antibody
• Liver biopsy to verify diagnosis
Isolated Unconjugated
Hyperbilirubinemia
• Drugs
• Probenecid, Rifampicin
• Gilbert’s Disease
• Autosomal recessive disorder
• 3 to 7 % of population
• Most common in white males
• Jaundice, increased unconjugated bilirubin (always < 6)
• Occurs when patient under stress/infection
• Crigler-Najjar type II
• Caused by gene mutation
• Reduced activity of Bilirubin UDP glucuronosyl
Clinical Jaundice in Adults
SERUM PROTEIN
ELECTROPHORESIS
Introduction
Plasma makes up 46-63% of blood
Similar to interstitial fluid
•
•
Differences:
•
•
•
•
levels of respiratory gases
Concentration and types of dissolved proteins
Straw colored or clear
http://www.piramoon.com/Graphics/
newsletters/blood-components.jpg
Composition of Plasma
• 92% water
• Proteins- for every 100ml for about 7.6 grams
• Albumins, Globulins, Fibrinogen
http://www.joinbiomedics.co
m/bloodcells.gif
Plasma Protein Distribution
Fibrinogen
Other Plasma Proteins
(4%)
(1%)
Albumin (60%)
Globulin (35%)
Globulin
(35%)
Albumin
(60%)
Fibrinogen (4%)
Other Plasma
Proteins (1%)
Albumins
• This water-soluble protein is the most
abundant of all the plasma proteins.
• Serum Albumin is the albumin present in
blood
• Is produced in the liver
• Maintains osmotic pressure of plasma
Globulins
• 4 different kinds of globulins present in blood: alpha 1 +
alpha 2, beta and gamma globulin
• are transport proteins.
• also serve as substrates for forming other
substances
• Gamma globulin makes up the largest
portion of globulin
Globulins Cont’d
• protein electrophoresis (SPEP) is performed to identify types of
globulins present in the blood.
• A way to diagnose diseases.
• Blood is drawn from a vein
• Proteins separated by size and charge
(separated into 4 types seen from last slide)
Too Much Gamma Globulin Protein?
• You may have many diseases, including:
• Chronic inflammatory disease
• Hyperimmunization
• Acute infection
• Waldenstrom’s macroglobulinemia
Fibrinogen
• Plasma protein that functions in blood clotting
• Synthesized in the liver
• Proactive protein and is converted to fibrin in certain
conditions
• Can cause heart attacks and strokes if there is too much
in the blood stream
Fibrinogen and Blood clotting
• A cascade of chemical reactions: use of platelets and
thrombin system
• When damage is detected, thrombin, a protease, is
released and converts fibrinogen into a fiber called
fibrin
• They stick to vessel walls and form a web like
structure and stop blood cells from passing
• In conversion, clotting proteins (such as calcium ions)
are removed leaving a fluid known as serum
Other Plasma Proteins
• remaining one 1% of plasma
• Peptide hormones
• Insulin
• Prolactin
• Glycoproteins
• TSH (thyroid- simulating hormone)
• FSH (follice stimulating hormone)
• LH (luteinizing hormone)
Plasma Proteins Come From…
• Liver
• Synthesizes 90% of the proteins
• Lymphocytes (lymphatic system)
• Makes the plasma cells  antibodies
• Endocrine organs
• Peptide hormones
Serum protein electrophoresis on agarose
gel
• Principle:
Serum proteins are negative charged at pH 8.6 (a buffer
helps to maintain a constant pH) and they move toward
the anode at the rate dependent on their net charge.
The separated proteins are fixed and stained by
amidoblack solution.
Serum protein electrophoresis on agarose
gel is a type of horizontal gel
electrophoresis
The figure was found at http://www.mun.ca/biology/desmid/brian/BIOL2250/Week_Three/electro4.jpg
Equipment used for the gel electrophoresis
in the practical training A1
power supply
(direct current)
containers for staining
and destaining gel
electrophoresis
chamber
applicator
Serum protein electrophoresis
Hydragel – agarose gel
•Serum proteins are
separated into 6 groups:
•Albumin
•α1 - globulins
•α2 - globulins
•β1 - globulins
•β2 - globulins
•γ - globulins
Figure is found at http://www.sebia-usa.com/products/proteinBeta.html#
Hydragel 15/30
• Gels with 15 or 30 wells
(serum samples) are used
in laboratories of clinical
biochemistry.
• Electrophoresis is also
used for separation of
isoenzymes,nucleic acids
and immunoglobulins
Figure is found at http://www.sebia-usa.com/products/proteinBeta.html#
Hydragel 15/30
• Hypergamma Control Pictured
• 16-30
Normal Control Pictured 1-15
Figure is found at http://www.sebia-usa.com/products/proteinControl.html
Evaluation of separated protein fractions
Densitometry
•
Densitometer is used for scanning of separated proteins in the
gel. Scanning the pattern gives a quantitative information about
protein fractions.
Figure is found at http://www.aafg.org
Serum proteins electrophoresis in diagnostics of
diseases
Normal pattern
•
Reference ranges:
Total protein
Albumin
α1-globulins
α2-globulins
β-globulins
γ-globulins
Figure is found at http://erl.pathology.iupui.edu/LABMED/INDEX.HTM
6.0 – 8.0 g/dL
3.5 – 5.0 g/dL
0.1 – 0.4 g/dL
0.4 – 1.3 g/dL
0.6 – 1.3 g/dL
0.6 – 1.5 g/dL
Acute inflammatory response
•
•
•
Immediate response occurs
with stress or inflammation
caused by infection, injury or
surgical trauma
normal or ↓ albumin
↑ α1 and α2 globulins
Figure is found at http://erl.pathology.iupui.edu/LABMED/INDEX.HTM
α1 α2-globulins
Chronic inflammatory response
α1 α2
• Late response is correlated
with chronic infection
(autoimmune diseases, chronic
liver disease, chronic infection,
cancer)
• normal or ↓ albumin
•↑α1 or α2 globulins
•↑↑ γ globulins
Figure is found at http://erl.pathology.iupui.edu/LABMED/INDEX.HTM
γ-globulins
Liver damage - Cirrhosis
•
•
•
•
Cirrhosis can be caused by
chronic alcohol abuse or viral
hepatitis
↓ albumin
↓ α1, α2 and β globulins
↑ Ig A in γ-fraction
Figure is found at http://erl.pathology.iupui.edu/LABMED/INDEX.HTM
γ-globulins
Hepatic cirrhosis
Decreased albumin (synthesis)
Increased gamma globulins (polyclonal gammopathy)
“- bridging”
Albumin
1
2

M. Zaharna Clin. Chem. 2009

441
Nephrotic syndrome
•
the kidney damage illustrates the
long term loss of lower molecular
weight proteins
(↓ albumin and IgG – they are
filtered in kidney)
•
retention of higher molecular weight
proteins (↑↑ α2-macroglobulin and
↑β-globulin)
α2-globulin β-globulin fractions
Figure is found at http://erl.pathology.iupui.edu/LABMED/INDEX.HTM
Nephrosis
Condition
Albumin
Nephrosis
Globulins
1
N
2
β
γ
N
Decreased albumin
Increased 2-macroglobulin
Decreased gamma globulins
Albumin
1
2


445
Hypogammaglobulinemia
Decreased gamma globulins
Albumin
1
2

Condition
Albumin
Hypogammaglobulinemia
N
Globulins
α1
α2
β
N
N
N

M. Zaharna Clin.
Chem. 2009
γ
Monoclonal gammopathy
• Monoclonal gammapathy is caused by
a sharp gamma globulin band
• monoclonal proliferation of β-lymphocytal
• clones. These „altered“ β-cells produce an
• abnormal immunoglobulin paraprotein.
• Production of paraprotein is associated
• with benign monoclonal gammopathy
• (leucemia) and multiple myeloma.
• Paraproteins can be found in a
• different position: between α-2 and
• γ-fraction.
Figure is found at http://erl.pathology.iupui.edu/LABMED/INDEX.HTM
• Monoclonalprotein present
• The patient was a 72 year old male
who presented with lower back pain.
• Quantitative immunoglobulin
measurements showed a large
increase in serum IgG, but decreased
IgA and IgM. Bone marrow exam
revealed a large increase in plasma
cells that were frequently aggregated.
• IFE on this patient's serum showed
the M protein was IgG kappa. A
diagnosis of multiple myeloma was
made.
http://erl.pathology.iupui.edu/labmed/Generator.cfm?Image=SPE
Monoclonal gammopathy
Albumin decreased
Sharp peak in gamma region
Albumin
1
2

M. Zaharna Clin. Chem. 2009

454
COMPLETE BLOOD
COUNT AND ANEMIA
Introduction
Complete Blood Count (CBC)
TEST
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
MPV
NEUT %
LYMPH %
MONO %
EOS %
BASO %
NEUT, ABS
LYMPH, ABS
MONO, ABS
EOS, ABS
BASO, ABS
RESULT
5.2
3.81 L
14.5
41.2
98
H
33.7 H
35.3
11.8
172
7.6
40.1
46.1
12.9
0.6
0.3
2085
2397
671
31
16
UNITS
x 1000/mm3
x 106/mm3
g/dL
%
fl
pg
%
%
x 1000/mm3
fl
%
%
%
%
%
cells/mm3
cells/mm3
cells/mm3
cells/mm3
cells/mm3
REF RANGE
3.9 - 11.1
4.20 - 5.70
13.2 - 16.9
38.5 - 49.0
80 - 97
27.5 - 33.5
32.0 - 36.0
11.0 - 15.0
140 - 390
7.5 - 11.5
38.0 - 80.0
15.0 - 49.0
0.0 - 13.0
0.0 - 8.0
0.0 - 2.0
1650 - 8000
1000 - 3500
40 - 900
30 - 600
0 - 125
Red Blood Count and RBC Indices
TEST
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
MPV
NEUT %
LYMPH %
MONO %
EOS %
BASO %
NEUT, ABS
LYMPH, ABS
MONO, ABS
EOS, ABS
BASO, ABS
RESULT
5.2
3.81 L
14.5
41.2
98
H
33.7 H
35.3
11.8
172
7.6
40.1
46.1
12.9
0.6
0.3
2085
2397
671
31
16
UNITS
x 1000/mm3
x 106/mm3
g/dL
%
fl
pg
%
%
x 1000/mm3
fl
%
%
%
%
%
cells/mm3
cells/mm3
cells/mm3
cells/mm3
cells/mm3
REF RANGE
3.9 - 11.1
4.20 - 5.70
13.2 - 16.9
38.5 - 49.0
80 - 97
27.5 - 33.5
32.0 - 36.0
11.0 - 15.0
140 - 390
7.5 - 11.5
38.0 - 80.0
15.0 - 49.0
0.0 - 13.0
0.0 - 8.0
0.0 - 2.0
1650 - 8000
1000 - 3500
40 - 900
30 - 600
0 - 125
Measuring RBCs (and the “Rule of
Threes”)
• Hematocrit (HCT) is the percent of a volume of whole blood occupied
by intact red blood cells. Measured in percent.
• Normal range for women: 36 - 46%
• Normal range for men: 41 - 53%
• Hemoglobin (HGB) measures the concentration of hemoglobin
expressed as grams of hemoglobin per deciliter (100 ml) of whole
blood.
• Normal range for women: 12 - 16 g/dL
• Normal range for men: 13.5 - 17.5 g/dL
• RBC count is the number of red blood cells per microliter of whole
blood. Measured in millions of RBCs per microliter of whole blood.
• Normal range for women: 4.0 - 5.2 x106/mm3
• Normal range for men: 4.5 - 5.9 x106/mm3
Red Blood Cell Indices
• Mean Corpuscular Volume (MCV) is the average size of red blood
cells.
• Normal range: 80-100 fL
• Low = “microcytic” (“too small”)
High = “macrocytic” (“too big”)
Normal = “normocytic” (“just right”)
• Red Cell Distribution Width (RDW) measures the variability in the
size of red blood cells.
• Normal range: 11.5-14.5%
• On a peripheral blood smear, high RDW is described as “anisocytosis”
• Mean Corpuscular Hemoglobin (MCH) is the amount of hemoglobin
in an average red blood cell.
• Normal range: 26-34 pg/cell
• Mean Corpuscular Hemoglobin Concentration (MCHC) is the
average concentration of hemoglobin in an average RBC.
• Normal range: 31-37 g/dL
• “Hypochromic” = “too pale”
“Normochromic” = “just right”
Red Blood Cell Indices
• Mean Corpuscular Volume (MCV) is the average size of
red blood cells.
• If anemia is present, MCV is a useful tool to guide further testing
• If anemia is not present, MCV is of little value:
• Low MCV without anemia suggests thalassemia minor (trait)
• High MCV without anemia can be caused by certain medications
(Dilantin, oral contraceptives, methotrexate) and is a “soft”
marker of possible alcohol overuse
• Red Cell Distribution Width (RDW) measures the
variability in the size of red blood cells.
• Not useful in the absence of anemia
Descriptive Terms Used on Peripheral
Smears
• Anisocytosis: marked variation in RBC sizes (visual
•
•
•
•
counterpart of increased RDW)
Hypochromia or hypochromasia: RBCs are paler than
normal because they contain less hemoglobin (visual
counterpart of decreased MCH)
Macrocytosis: increased number of large RBCs (visual
counterpart of increased MCV)
Microcytosis: increased number of small RBCs (visual
counterpart of decreased MCV)
Poikilocytosis: marked variation in the shape of RBCs
Reticulocyte Count
• Reticulocytes are “young” red blood cells that
were recently released from the bone marrow.
• Normally, reticulocytes comprise 0.5 - 2.5% of
all red blood cells.
• Increased reticulocytes (reticulocytosis) is a
normal response to blood loss or anemia.
Since reticulocytes are larger, the MCV (and
RDW) may be elevated.
• The combination of anemia with a low or
normal reticulocyte count indicates that the
bone marrow is unable to respond normally,
either due to lack of essential ingredients (iron
deficiency, vitamin B12 or folate deficiency),
bone marrow disease, or chronic disease.
463
For Financial Professional Use Only
COMPLETE BLOOD
COUNT AND ANEMIA
Anemia
Anemia
• Defined as a reduction in one or more of the major RBC
measurements:
• Hgb: measures the concentration of the major oxygen carrying
pigment in whole blood
• Hct: percent of a sample of whole blood occupied by intact RBCs
• RBC Count: number of RBCs contained in a specified volume of
whole blood
• All factors are dependent on the RBC mass and the
plasma volume
Signs and Symptoms of Anemia
• Dependent on the degree of anemia, the rate at it
evolved, and the oxygen demand
• Normally, RBCs carry oxygen linked to Hgb from
the lung to tissue capillaries, where oxygen is
released
• Symptoms result from decreased oxygen delivery
or acute blood loss (hypovolemia)
• Compensatory mechanisms allow one to
tolerated lower levels of Hgb/Hct
Anemia: History
• Is the patient bleeding?
• NSAIDs, ASA
• Past medical history of anemia? Family history?
• Alcohol, nutritional questions
• Liver, renal diseases
• Menstrual history if applicable
• Ethnicity
• Environmental/work toxins (ie lead)
Symptoms of Anemia
• Decreased O2 delivery
• Hypovolemia if acute loss
• Exertional dyspnea, fatigue, palpitations, “bounding
pulses”
• Severe: heart failure, angina, MI
• “Pica”– craving for paper products
• Pagophagia– craving for ice
Signs of Anemia
• Tachycardia,
• Pallor
• Jaundice
• Koilonychia or “Spoon nails”
• Splenomegaly, lymphadenopathy
• Petechiae, ecchymoses
• Atrophy of tongue papillae
Pallor
Koilonychia or “Spoon nails
Approach to Anemia
• Classification:
• Kinetic Approach –mechanism responsible
• Decreased RBC production
• Increased RBC destruction
• Blood Loss
• Morphologic Approach – alteration in RBC size
• Macrocytic
• Normocytic
• Microcytic
Kinetic Approach
• Decreased RBC Production
– Lack of nutrients (Fe, B12, Folate) due to diet, malabsorbtion
– Bone Marrow Disorders
– Bone Marrow Suppression
– Drugs, chemotherapy, radiation
– Low levels of trophic hormone levels which stimulate RBC
production
– Epo, Thyroid Hormone, Androgens
– Chronic disease/inflammation
– Causes decreased Fe absorbtion from GIT, decreased Fe release
from macrophages, reduction of Epo
Kinetic Approach
• Increased RBC Destruction
• Inherited and acquired hemolytic anemias
•
•
Inherited: Hereditary Spherocytosis, sickle cell disease, thalassemia
Acquired:
• Blood Loss
• One of the most common causes of anemia
• Not only lose RBCs, but also the Fe in these cells, which leads to
Fe deficiency
Morphologic Approach
• Macrocytic
– Reticulocytosis
– Drugs interfering with nucleic acid synthesis
– Abnormal nucleic acid metabolism of erythroid precursors
– Abnormal RBC Maturation
– liver disease, hypothyroidism
• Normocytic
• Microcytic
– Reduced iron availability
– Reduced Heme synthesis
– Reduced globin production
Hemolytic Anemia
• Anemia due to shortened survival of circulating RBCs
(Normal: 110-120 days)
– Hemolysis <100 days
• With intact bone marrow:
• Anemia  Compensatory increase in Epo secretion  Enhances
RBC production (reticulocytosis)  Reduces degree of anemia
• This is most commonly seen with hemolytic anemia, but not
specific to hemolysis (can also be seen with acute blood loss)
Causes of Hemolysis - Intrinsic
• Generally, a hereditary disorder
• Intrinsic hemolysis is caused by defects in Hgb, RBC
membrane or metabolic factors needed to generate ATP
•
Examples
•
Thalassemia (defect in alpha or beta globin chains)
•
Spherocytosis (missing RBC membrane proteins)
•
G6PD deficiency (abnormality in reducing power (NADPH))
Causes of Hemolysis - Extrinsic
• Acquired disorder
• Causes include:
• Ab directed against RBC membrane components
•
AIHA (Auto Immune Hemolytic Anemia), delayed transfusion
reaction
• Stasis/trapping/destruction in spleen (hypersplenism)
• Trauma
• Prosthetic heart valve
• Exposure to compounds with oxidant potential
• Sulfonamide in those with G6PD
• Destruction of RBC by pathogens
• Malaria, babesiosis
Site of Hemolysis
• Dependant on the severity and type of cell alteration
(alteration in RBC membrane)
• Severe damage  immediate lysis in the circulation
(INTRAVASCULAR)
• Less severe damage  cell destruction is via the
monocyte-macrophage system in the liver, spleen, BM,
lymph node (EXTRAVASCULAR)
Intravascular Hemolysis
• Intravascular hemolysis  Release of Hgb
into the plasma
• Free Hgb binds to haptoglobin  Hgbhaptoglobin complex is taken up by liver 
Decrease in plasma haptoglobin
• Free Hgb breaks down to alpha-beta
dimers  filtered by glomerulus 
Hemoglobinuria
Features of Hemolysis
• Rapid fall in Hgb
• Increased LDH, decreased Haptoglobin
• Jaundice (elevated indirect bilirubin)
• Splenomegaly
• pigmented gallstones
• Abnormally shaped RBCs
• Reticulocytosis
Labs
 LDH: elevated
 Indirect bilirubin: elevated (due to catabolism of Hgb)
 Haptoglobin: decreased
 Binds to Hgb and taken up by liver
 In a series of reports:
 Elevated LDH, low Haptoglobin was 90% specific
 Normal LDH, Haptoglobin >25 was 92% sensitive for ruling out
hemolysis
 Reticulocyte Count: elevated
 Normal is 0.5-1.5%
 Anemia leads to increase Epo production leading to a
reticulocytosis (4-5% increase above baseline)
IRON-DEFICIENCY ANEMIA
• Iron deficiency is one of the most prevalent forms of
malnutrition. Globally, 50% of anemia is attributable to iron
deficiency and accounts for approximately 841,000
deaths annually worldwide. Africa and parts of Asia bear
71% of the global mortality burden; North America
represents only 1.4% of the total morbidity and mortality
associated with iron deficiency.
IRON METABOLISM
• Iron is normally absorbed by active transport across the wall
of the duodenum and upper part of the jejunum.
• If large amounts of iron are ingested the active transport
mechanism is overtaken by passive diffusion..
• Iron is best absorbed in the ferrous (reduced) form (Fe++).
• Absorption is improved by reducing substances, e.g. ascorbic
acid (vitamin C).
• Iron absorption is normally relative to the needs of the body.
• About 10% of dietary iron is usually taken up by the body but
this can increase several-fold in iron deficiency, or reduce if the
body has a surplus.
IRON METABOLISM
• Most iron in the body is in the form of haem; present in
large amounts in red cells, muscle and liver where it is
essential for oxygen supply.
• Iron is also present in many enzyme systems, e.g.
electron transport systems.
• The transport and storage of iron mainly involves three
proteins:
•
•
transferrin
transferrin receptor (TfR)
ferritin
IRON METABOLISM
• Transferrin actively binds and transports iron in the body
and can be estimated by measuring the serum total iron
binding capacity (TIBC).
• Transferrin increases in iron deficiency and decreases
with iron overload, liver disease, infection, malignancy
and protein deficiency.
IRON METABOLISM
• Excess
iron is stored mainly in macrophages as
haemosiderin; an insoluble protein-iron complex formed
by lysosomal degeneration of ferritin.
• Ferritin is the water soluble protein-iron complex formed
when iron combines with apoferritin. Iron in ferritin is in
the ferric form (Fe+++) and must be reduced before it can
be utilised.
LABORATORY INVESTIGATION OF IRON
DEFICIENCY ANAEMIA
• Full Blood Count
• Serum Ferritin
• Serum Iron & Total Iron Binding Capacity
• Serum Transferrin
• Bone Marrow
Anemia of Chronic Disease
• A normocytic, normochromic chronic anemia due to
chronic infections (TB) or chronic inflammations (RA,
neoplatic conditions) as well as chronic illnesses
(diabetes, liver disease)
• Usually mild, progressive and asymptomatic
Anemia of Chronic Disease
• Etiology
• disruption of iron metabolism
• defect in red cell production
• shortening of erythrocyte life span
• Incidence
second most common to iron deficiency
Diagnostics
• Normal to increased iron stores with concurrent
low serum iron
• serum iron-decreased
• TIBC-decreased
• serum ferritin-increased
• Hemoglobin-decreased
• Hematocrit- decreased
• MCV- normal
• Reticulocytes-decreased
COMPLETE BLOOD
COUNT AND ANEMIA
White Blood Count with Differential
TEST
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
MPV
NEUT %
LYMPH %
MONO %
EOS %
BASO %
NEUT, ABS
LYMPH, ABS
MONO, ABS
EOS, ABS
BASO, ABS
RESULT
5.2
3.81 L
14.5
41.2
98
H
33.7 H
35.3
11.8
172
7.6
40.1
46.1
12.9
0.6
0.3
2085
2397
671
31
16
UNITS
x 1000/mm3
x 106/mm3
g/dL
%
fl
pg
%
%
x 1000/mm3
fl
%
%
%
%
%
cells/mm3
cells/mm3
cells/mm3
cells/mm3
cells/mm3
REF RANGE
3.9 - 11.1
4.20 - 5.70
13.2 - 16.9
38.5 - 49.0
80 - 97
27.5 - 33.5
32.0 - 36.0
11.0 - 15.0
140 - 390
7.5 - 11.5
38.0 - 80.0
15.0 - 49.0
0.0 - 13.0
0.0 - 8.0
0.0 - 2.0
1650 - 8000
1000 - 3500
40 - 900
30 - 600
0 - 125
Absolute Neutrophil Count
TEST
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
MPV
NEUT %
LYMPH %
MONO %
EOS %
BASO %
NEUT, ABS
LYMPH, ABS
MONO, ABS
EOS, ABS
BASO, ABS
RESULT
5.2
3.81 L
14.5
41.2
98
H
33.7 H
35.3
11.8
172
7.6
40.1
46.1
12.9
0.6
0.3
2085
2397
671
31
16
UNITS
x 1000/mm3
x 106/mm3
g/dL
%
fl
pg
%
%
x 1000/mm3
fl
%
%
%
%
%
cells/mm3
cells/mm3
cells/mm3
cells/mm3
cells/mm3
REF RANGE
3.9 - 11.1
4.20 - 5.70
13.2 - 16.9
38.5 - 49.0
80 - 97
27.5 - 33.5
32.0 - 36.0
11.0 - 15.0
140 - 390
7.5 - 11.5
38.0 - 80.0
15.0 - 49.0
0.0 - 13.0
0.0 - 8.0
0.0 - 2.0
1650 - 8000
1000 - 3500
40 - 900
30 - 600
0 - 125
5.2 x 1000 = 5200
5200 x .401 = 2085
Types of White Blood Cells - What’s the
Diff?
• Neutrophils – also called a
variety of other names on
CBC reports, including:
polys
• PMNs
• segs
• bands or stabs (immature
neutrophils indicate acute
infection)
•
• Lymphocytes
• Monocytes
• Eosinophils
• Basophils
500
For Financial Professional Use Only
WBC Differential: Neutrophils
Possible Causes of
Neutrophilia:
Common: bacterial infections,
inflammatory disorders, stress,
certain drugs (especially
prednisone), pregnancy
Rare: leukemias
Possible Causes of
Neutropenia:
Common: chronic benign
neutropenia (some forms are
familial), chemotherapy
Uncommon: systemic lupus
erythematosus, immunodeficiency
states
Leukocytosis
• An elevated WBC count is termed “leukocytosis”
• Normal level is 4,400 to 10,000 WBC per mm 3
• This can result from many causes, principally infections,
inflammatory disorders, and medications
• Cancer and myeloproliferative disorders can also cause
high, sometimes extremely high, WBC counts
• Treatment is aimed at the underlying cause
• Death may result from the underlying cause such as
severe infection or cancer (leukemia)
WBC Differential: Lymphocytes
Possible Causes of
Lymphocytosis:
Common: viral infections
Possible Causes of
Lymphopenia:
Uncommon: inflammatory bowel
disease
Uncommon: systemic lupus
erythematosus, immunodeficiency
states
Rare: chronic lymphocytic
leukemia, vasculitis
Rare: aplastic anemia, Hodgkin’s
disease
WBC Differential: Monocytes
Possible Causes of
Monocytosis:
Decreased Levels:
Common: recovery phase after
infections
Uncommon: certain infections (TB,
malaria), inflammatory bowel
disease
Rare: myeloproliferative disorders
including myeloid metaplasia,
polycythemia vera, certain forms of
leukemia and lymphoma
---
WBC Differential: Eosinophils
Possible Causes of
Eosinophilia:
Decreased Levels:
Common: allergic disorders
(including drug reactions)
Uncommon: parasite infection,
lupus, rheumatoid arthritis
Rare: hypereosinophilic syndrome,
diffuse skin diseases, some forms
of leukemia and lymphoma,
Löffler’s endocarditis
---
WBC Differential: Basophils
Possible Causes of Basophilia:
Rare: leukemias, myeloid
metaplasia, Hodgkin’s disease
Decreased Levels:
---
Platelet Count
TEST
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
MPV
NEUT %
LYMPH %
MONO %
EOS %
BASO %
NEUT, ABS
LYMPH, ABS
MONO, ABS
EOS, ABS
BASO, ABS
RESULT
5.2
3.81 L
14.5
41.2
98
H
33.7 H
35.3
11.8
172
7.6
40.1
46.1
12.9
0.6
0.3
2085
2397
671
31
16
UNITS
x 1000/mm3
x 106/mm3
g/dL
%
fl
pg
%
%
x 1000/mm3
fl
%
%
%
%
%
cells/mm3
cells/mm3
cells/mm3
cells/mm3
cells/mm3
REF RANGE
3.9 - 11.1
4.20 - 5.70
13.2 - 16.9
38.5 - 49.0
80 - 97
27.5 - 33.5
32.0 - 36.0
11.0 - 15.0
140 - 390
7.5 - 11.5
38.0 - 80.0
15.0 - 49.0
0.0 - 13.0
0.0 - 8.0
0.0 - 2.0
1650 - 8000
1000 - 3500
40 - 900
30 - 600
0 - 125
Mean Platelet Volume (MPV)
• “Young” platelets, recently released from the bone
marrow, are typically slightly larger
• Often elevated in immune or idiopathic thrombocytopenic
purpura (ITP)
• In an individual with low platelet count
(thrombocytopenia):
• Increased MPV indicates normal bone marrow response
• Decreased or low normal MPV may indicate impaired bone marrow
response
COMPLETE BLOOD
COUNT AND ANEMIA
Case study
Anemia
Case Study #1
A 72 year old
male has the
CBC findings
shown.
Peripheral
RBCs are
hypochromic
& microcytic.
Anemia
Case Study #1
• What test would you order for this
patient?
• A-Hemoglobin Electrophoresis
• B-Retic count
• C-Stool for occult blood
• D-B12 Assay
• E-Bone marrow biopsy
Anemia
Case Study #1
• Two questions:
• What is your diagnosis?
• What is the next step for this patient?
Anemia
Case Study #1
• Answers
• Question 1
• Likely Iron Deficiency Anemia
• Question 2
• Colonoscopy
Anemia
Case Study #2
A 48 year old male
has become
progressively more
fatigued at the end of
the day. This has
been going on for
months. In the past
month he has noted
paresthesias with
numbness in his feet.
A CBC demonstrates
the findings shown.
Anemia
Case Study #2
A peripheral blood
smear (the slide is
representative of this
condition) shows red
blood cells displaying
macro- ovalocytosis
and neutrophils with
hypersegmentation.
Anemia
Case Study #2
Which of the following tests would be most useful to
determine the etiology?
A. Hemoglobin electrophoresis
B. Reticulocyte count
C. Stool for occult blood
D. Vitamin B12 assay
E. Bone marrow biopsy
Anemia
Case Study #2
Questions:
•
•
What is the diagnosis from these findings?
•
How do you explain the neurologic findings?
Anemia
Case Study #2
• Answers:
• Question 1
• This is a macrocytic (megaloblastic) anemia. The neurologic findings
suggest vitamin B12 deficiency (pernicious anemia).
• Question 2
• The B12 deficiency leads to degeneration in the spinal cord
(posterior and lateral columns).
Case # 3
TEST
RESULT
• 57 yo
WBC
RBC
3.46 L
• mild type 2 diabetes,
HGB
controlled on oral
medications, HbA1c 6.1%
• routine follow-up for diabetes,
no complications, CBC done
as routine test
519
7.5
UNITS
x 1000/mm3
x
REF RANGE
3.9 - 11.1
106/mm3
4.60 - 6.20
10.1 L
g/dL
14.0 - 18.0
HCT
29.6 L
%
40.0 - 54.0
MCV
85.6
fl
80 – 94
MCH
29.3
pg
27 - 33
MCHC
34.2
%
32.0 - 36.0
RDW
13.9
%
11.0 - 15.0
PLT
222
NEUT %
58.0
%
40 - 79
LYMPH %
29.5
%
15 - 45
MONO %
7.0
%
0 - 11
EOS %
BASO %
5.2
0.3
%
%
0-6
0-3
NEUT, #
4.4
x103 uL
1.8 - 8.7
LYMPH, #
2.2
x103 uL
0.7 - 5.0
MONO, #
0.5
x103
uL
0.0 - 1.2
EOS, #
0.4
x103 uL
0.0 - 0.7
BASO, #
0
x103 uL
0.0 - 0.3
For Financial Professional Use Only
x
1000/mm3
140 - 390
Case # 3 (continued)
• Serum vitamin B12 and folate
•
•
•
•
levels were normal
Iron studies showed low serum
ferritin and a low transferrin
saturation, consistent with iron
deficiency
Colonoscopy was normal
Upper endoscopy showed
moderate gastritis and
esophagitis with no evidence of
active bleeding
Hemoglobin improved with
administration of iron
520
Iron-poor RBCs are pale and small
(low MCV and MCH)
For Financial Professional Use Only
Case # 4
TEST
• 47 yo female
• routine gynecologic visits,
CBC done as part of routine
exam last year
521
RESULT
UNITS
REF RANGE
WBC
4.7
x 109/L
4.4 - 11.3
RBC
5.6
x 1012/L
4.7 - 6.1
HGB
10.5
L
g/dL
12.3 - 15.3
HCT
31.6
L
%
35.9 - 44.6
MCV
65.8
L
fL
80 - 96
MCH
19.9
L
pg
27.5 - 33.2
MCHC
26.7
L
%
33.4 - 35.5
RDW
13.0
%
11.5 - 14.5
PLT
249
x 109/L
100 - 450
For Financial Professional Use Only
LABORATORY
ASSESSMENT OF
ENDOCRINE DISEASE
MALIK ALQUB MD. PHD.
Approach to the Patient with
Endocrine Disorders
• Endocrine diseases can be divided into three major types
of conditions:
(1) hormone excess,
(2) hormone deficiency,
(3) hormone resistance
Disorders of the Thyroid Gland
• The thyroid gland produces two related hormones,
thyroxine (T4) and triiodothyronine (T3) . Acting through
thyroid hormone receptors α and β, these hormones
play a critical role in cell differentiation during
development and help maintain thermogenic and
metabolic homeostasis in the adult. Autoimmune
disorders of the thyroid gland can stimulate
overproduction of thyroid hormones (thyrotoxicosis) or
cause glandular destruction and hormone deficiency
(hypothyroidism).
Follicles: the Functional Units of the
Thyroid Gland
Follicles Are the Sites
Where Key Thyroid
Elements Function:
• Thyroglobulin (Tg)
• Tyrosine
• Iodine
• Thyroxine (T4)
• Triiodotyrosine (T3)
Production of T4 and T3
• T4 is the primary secretory product of the thyroid
gland, which is the only source of T4
• The thyroid secretes approximately 70-90 g of T4
per day
• T3 is derived from 2 processes
15-30 g
• About 80% of circulating T3 comes from deiodination of T4
in peripheral tissues
• About 20% comes from direct thyroid secretion
• The total daily production rate of T3 is about
T4: A Prohormone for T3
• T4 is biologically inactive in target tissues until
converted to T3
• Activation occurs with 5' iodination of the outer ring of T 4
• T3 then becomes the biologically active hormone
responsible for the majority of thyroid hormone
effects
Sites of T4 Conversion
• The liver is the major extrathyroidal T4 conversion
site for production of T3
• Some T4 to T3 conversion also occurs in the kidney
and other tissues
T4 Disposition
• Normal disposition of T4
• About 41% is converted to T3
• 38% is converted to reverse T3 (rT3), which is
metabolically inactive
• 21% is metabolized via other pathways, such as
conjugation in the liver and excretion in the bile
• Normal circulating concentrations
• T4 4.5-11 g/dL
• T3 60-180 ng/dL (~100-fold less than T4)
Transport of Thyroid Hormones
• Thyroid hormones are not very soluble in water (but
are lipid-soluble).
• Thus, they are found in the circulation associated with
binding proteins:
- Thyroid Hormone-Binding Globulin (~70% of
hormone)
- Pre-albumin, (~15%)
- Albumin (~15%)
• Less than 1% of thyroid hormone is found free in the
circulation.
• Only free and albumin-bound thyroid hormone is
biologically available to tissues.
Regulation of Thyroid Hormone Levels
• Secretion of the thyroid hormones T4 (thyroxine) and T3
(triiodothyronine) is regulated by pituitary thyrotropin
(TSH).
• Thyrotropin-releasing hormone (TRH) increases the
secretion of thyrotropin (TSH), which stimulates the
synthesis and secretion of trioiodothyronine (T3) and
thyroxine (T4) by the thyroid gland. T3 and T4 inhibit the
secretion of TSH, both directly and indirectly by
suppressing the release of TRH. sites.
LABORATORY EVALUATION
• TSH
• Free T4 (thyroxine)
• Free T3 (triiodothyronine)
LABORATORY EVALUATION
• The enhanced sensitivity and specificity of TSH assays
have greatly improved laboratory assessment of thyroid
function. Because TSH levels change dynamically in
response to alterations of T4 and T3, a logical approach
to thyroid testing is to first determine whether TSH is
suppressed, normal, or elevated. a normal TSH level
excludes a primary abnormality of thyroid function.
• The finding of an abnormal TSH level must be followed by
measurements of circulating thyroid hormone levels to
confirm the diagnosis of hyperthyroidism (suppressed
TSH) or hypothyroidism (elevated TSH).
LABORATORY EVALUATION
• Total thyroid hormone levels are elevated when TBG is
increased due to estrogens (pregnancy, oral
contraceptives, hormone therapy, tamoxifen, selective
estrogen receptor modulators, inflammatory liver disease)
and decreased when TBG binding is reduced (androgens,
nephrotic syndrome).
• For most purposes, the unbound T4 level is sufficient to
confirm thyrotoxicosis, but 2–5% of patients have only an
elevated T3 level (T3 toxicosis). Thus, unbound T3 levels
should be measured in patients with a suppressed TSH
but normal unbound T4 levels.
Overview of Thyroid Disease States
• Disorders of the thyroid are common and consist of 2
general presentations:
• changes in the size or shape of the gland or changes in secretion
of hormones from the gland.
• Hypothyroidism refers to the inadequate production of thyroid hormone
or diminished stimulation of the thyroid by TSH;
• hyperthyroidism refers to those conditions in which thyroid hormones
are excessively released due to gland hyperfunction.
Hypothyroidism
•
Hypothyroidism is a disorder with multiple
causes in which the thyroid fails to
secrete an adequate amount of thyroid
hormone
•
The most common thyroid disorder
•
Usually caused by primary thyroid gland failure
•
Also may result from diminished stimulation of the
thyroid gland by TSH
Hyperthyroidism
• Hyperthyroidism refers to excess synthesis
and secretion of thyroid hormones by the
thyroid gland, which results in accelerated
metabolism in peripheral tissues
Hypothyroidism: Types
• Primary hypothyroidism
• From thyroid destruction
• Central or secondary hypothyroidism
• From deficient TSH secretion, generally due to sellar lesions
such as pituitary tumor or craniopharyngioma
• Infrequently is congenital
• Central or tertiary hypothyroidism
• From deficient TSH stimulation above level of pituitary—ie,
lesions of pituitary stalk or hypothalamus
• Is much less common than secondary hypothyroidism
Bravernan LE, Utiger RE, eds. Werner & Ingbar's The Thyroid.
8th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2000.
Persani L, et al. J Clin Endocrinol Metab. 2000; 85:3631-3635.
Hypothyroidism:
Underlying Causes
• Congenital hypothyroidism
• Agenesis of thyroid
• Defective thyroid hormone biosynthesis due to
enzymatic defect
• Thyroid tissue destruction as a result of
• Chronic autoimmune (Hashimoto) thyroiditis
• Radiation (usually radioactive iodine treatment
for thyrotoxicosis)
• Thyroidectomy
• Other infiltrative diseases of thyroid (eg,
hemochromatosis)
Clinical Features of Hypothyroidism
Tiredness
Puffy Eyes
Slower Thinking
Enlarged Thyroid (Goiter)
Moodiness/ Irritability
Hoarseness/
Deepening of Voice
Depression
Inability to Concentrate
Thinning Hair/Hair Loss
Loss of Body Hair
Dry, Patchy Skin
Weight Gain
Cold Intolerance
Elevated Cholesterol
Family History of Thyroid
Disease or Diabetes
Persistent Dry or Sore Throat
Difficulty Swallowing
Slower Heartbeat
Menstrual Irregularities/
Heavy Period
Infertility
Constipation
Muscle Weakness/
Cramps
Chronic Autoimmune Thyroiditis
(Hashimoto Thyroiditis)
• Occurs when there is a severe defect in thyroid
hormone synthesis
• Is a chronic inflammatory autoimmune disease characterized
by destruction of the thyroid gland by autoantibodies against
thyroglobulin, thyroperoxidase, and other thyroid tissue
components
• Patients present with hypothyroidism, painless goiter, and other
overt signs
• Persons with autoimmune thyroid disease may have
other concomitant autoimmune disorders
• Most commonly associated with type 1 diabetes mellitus
Laboratory Evaluation
• A normal TSH level excludes primary (but not secondary)
hypothyroidism. If the TSH is elevated, an unbound T4
level is needed to confirm the presence of clinical
hypothyroidism.
• TSH when used as a screening test, because it will not
detect subclinical hypothyroidism. Circulating unbound T3
levels are normal in about 25% of patients, reflecting
adaptive deiodinase responses to hypothyroidism. T3
measurements are, therefore, not indicated.
• the etiology is usually easily established by demonstrating
the presence of TPO antibodies, which are present in
>90% of patients with autoimmune hypothyroidism.
Subacute (de Quervain’s) Thyroiditis
• Preceding viral infection
• Infiltration of the gland with granulomas
• Painful goitre
• Hyperthyroid phase  Hypothyroid phase
Signs and Symptoms of
Hyperthyroidism
Nervousness/Tremor
Mental Disturbances/
Irritability
Difficulty Sleeping
Bulging Eyes/Unblinking Stare/
Vision Changes
Enlarged Thyroid (Goiter)
Menstrual Irregularities/
Light Period
Frequent Bowel Movements
Warm, Moist Palms
First-Trimester Miscarriage/
Excessive Vomiting in Pregnancy
Hoarseness/
Deepening of Voice
Persistent Dry or Sore Throat
Difficulty Swallowing
Palpitations/
Tachycardia
Impaired Fertility
Weight Loss or Gain
Heat Intolerance
Increased Sweating
Sudden Paralysis
Family History of
Thyroid Disease
or Diabetes
Hyperthyroidism
Underlying Causes
• Signs and symptoms can be caused by any
disorder that results in an increase in circulation
of thyroid hormone
• Toxic diffuse goiter (Graves disease)
• Toxic uninodular or multinodular goiter
• Painful subacute thyroiditis
• Silent thyroiditis
• Toxic adenoma
• Iodine and iodine-containing drugs and radiographic
contrast agents
Graves Disease
(Toxic Diffuse Goiter)
• The most common cause of hyperthyroidism
• Accounts for 60% to 90% of cases
• Incidence in the United States estimated at 0.02% to
0.4% of the population
• Affects more females than males, especially in the
reproductive age range
• Graves disease is an autoimmune disorder
possibly related to a defect in immune
tolerance
Thyroid Nodular Disease
• Thyroid gland nodules are common in the
general population
• Most thyroid nodules are benign
• Less than 5% are malignant
• Only 8% to 10% of patients with thyroid nodules
have thyroid cancer
Multinodular Goiter (MNG)
• MNG is an enlarged thyroid gland containing
multiple nodules
• The thyroid gland becomes more nodular with
increasing age
• In MNG, nodules typically vary in size
• Most MNGs are asymptomatic
• MNG may be toxic or nontoxic
• Toxic MNG occurs when multiple sites of autonomous
nodule hyperfunction develop, resulting in thyrotoxicosis
• Toxic MNG is more common in the elderly
CUSHINGS, ADDISONS
AND ACROMEGALY
Cushings: Disease vs. Syndrome
• Cushings Disease is the result of a pituitary tumour
secreting inappropriate ACTH
• Cushings Syndrome causes the same symptoms, but is
caused by overproduction of adrenal hormones. It
encompasses all other forms of Cushings
• Basically:
• Disease = increased cortisol from pituitary
• Syndrome = all other sources
Aetiology
Harvey Cushing in 1932
Endogenous Causes:
65% = pituitary
25% = adrenals
= Females 5:1 ratio and ages 25-40
10% = ectopic source (small cell lung ca), non-pituitary, ACTH producing tumour
Exogenous Causes:
Iatrogenic Steroids (Asthma, RA, palliative)
Higher incidence in people with: DM, HTN, Obesity and Osteoporosis
S&S
SWEDISH
S – Spinal tenderness
W – Weight gain
E – Easily bruise
D – Diabetes
I – Intercapsular fat pad
S – Striae
H – HTN
Differential Diagnosis
• Pseudo-Cushingoid:
• Chronic severe anxiety and/or depression
• Prolonged excess alcohol consumption
• Obesity
• Poorly controlled diabetes
• HIV infection
Investigations
• Bloods tests FBC
• U/E – low K
• Special tests:
• Cortisol at midnight and 0900 (loss of diurnal variation –
should be low at midnight <550) – less reliable
• 24 hour urinary cortisol – 3 collections
• 24 hour salivary cortisol sampling
• Dexamethasone Suppression Test
Dexamethasone Suppression Test
• Overnight Low dose = Baseline reading, Dex 1mg given at 11pm,
measure cortisol at 8am
• If cortisol low (<50nmol/L) = normal
• If cortisol high (>50nmol/L) = investigate further – Cushings syndrome
• Localising the lesion:
• Plasma ACTH
• if undetectable = adrenal cause (as adrenal cause independent of
ACTH)
• If detected – proceed to high dose dex suppression test
• High dose
• if >90% suppression – pituitary
• if less/no suppression – ectopic source
Addisons: Aetiology
• Dr Thomas Addison in 1855
• True Addisons:
• Affects 1 in 10000 in UK – rare
• Common presentation between 30 and 50
• Affects women more
• 70-90% have autoimmune basis – cytotoxic T cells
• Clinical and biochemical insufficiency only occurs once >90% of the
gland is destroyed.
• Primary = adrenals
• Secondary = pituitary
• Tertiary = hypothalamus
Aetiology continued
• TB (most common worldwide)
• infections – AIDS, fungal
• Adrenal haemorrhage (caused by sepsis, meningitis)
• Metastatic spread to adrenals
• Amyloidosis
• Adrenalectomy
• Genetic/congenital defects
• Addsions = long term steroids leading to suppression of
HPA axis
S&S
Investigations
• Blood tests:
• Low Na, low cortisol
• Low aldosterone causing high K,
• High adrenocorticotrophic hormone (ACTH)
• Low glucose
Acromegaly: Aetiology
• Pituitary tumour >99% (very rarely ectopic (carcinoid)
• M:F = 1:1
• 30-50y old
• 5% genetic association with MEN1
• GH stimulates soft tissue and skeletal growth through
increased secretion of IGF-1 and secretion inhibited by
somatostatin
S&S
• A – Arthopathy
• B – BP high
• C – Carpal tunnel
• D – Diabetes & HF
• E – Enlarged tongue/heart
• F – Field defect - hemianopia
Investigations
• Bloods?
• Random GH levels – not helpful (stress/sleep/pregnancy)
• IGF-1 increased in 75% people
• Special tests:
• OGTT:
• Measure glucose and GH at 0,30,60,90,120,150 mins
• Normally glucose causes GH suppression
• If Acromegaly – no GH suppression
• False +ves – puberty, pregnancy, hepato-renal
disease, anorexia, DM
Case presentations
• 30 year old woman presents feeling unwell and dizzy, loss
of weight, decreased libido and darker skin but also some
areas of very light skin. Treated for anorexia 2 years ago
• 50 year old man presents saying his rings are becoming
tighter on his hands and he’s had to buy bigger shoes.
Keeps walking into things
• 30 year old woman has noticed weight gain especially
around face and abdomen, hair loss, bruises easily,
urinating more often