INTRODUCTION TO LABORATORY
MEDICINE
DEFINITION
Laboratory medicine a specialty in which
pathologists provide testing of patient samples
(usually blood or urine) in several different
areas.
Determination of the level of enzymes in blood in case
of heart attack or
 Level of glucose (sugar) in the blood of a patient with
diabetes.
 The presence of bacteria and other microorganisms.
 Blood cells studies for various types of anemias

COURSE OBJECTIVES
application of basic science to those clinical
disciplines practiced by the medical laboratory
scientist.
 the scope of Laboratory Medicine, and of its
potential applications.
 How to analyze various samples under certain
circumstances.

COURSE CONTENTS
Clinical Biochemistry
 Cardiac profiles
 Liver and renal panels
 Bone metabolism
 Lipid chemistry
 Special chemistry
 Cardiovascular markers
 Tumour markers
 Nutritional markers
 Calculi

Immunology and Immunodiagnostics
 Drug monitoring
 Urine and serum proteins
 Autoimmune disease testing
 Endocrinology tests
 Fertility testing
 Point-of-Care Testing
 Cardiac markers
 Glucose monitoring program
 Blood gases and metabolites
 Routine chemistry panels
 Routine urinalysis and pregnancy screening
 Coagulation
 Complete Blood Counts


Urine toxicology screening
Laboratory Hematology
 Routine and special hematology
 Hemoglobinopathy studies
 Special stains
 Hematopathology
 Bone marrow consultations and interpretive
report
 Flow cytometry
 CD 34 (stem cell) enumeration
 CD4/CD8 monitoring
 Leukemia/lymphoma immunophenotyping
 PNH

Special coagulation
 Coagulation profiles, screening and factors and
inhibitors
 Platelet studies
 Thrombophilia testing
 Microbiology
 Bacterial culture and sensitivities
 Blood cultures
 Molecular typing of organisms
 Viral detection methodologies
 HIV viral load -public health lab accredited
site for viral load
 Chlamydia detection
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Infection control
 Reference centre for medical microbiology and infectious
diseases
 Detection and typing of epidemiologically significant
organisms
Serology
 Clostridium difficile toxin testing
 Wide range of viral and non-viral serologies
Molecular Diagnostic Testing
 Wide range of molecular testing for viral and bacterial
agents
 Mycology
 Fungus detection
 Cells/tissues/organ donor testing
Blood Bank/Donor Center
 Concepts of immunohematology and histocompatibility
 Blood transfusion services and quality assurance
 Blood donation and storage of blood
 Blood grouping
 Compatibility testing
RECOMMENDED BOOKS
Textbook:
District laboratory practice in tropical
countries by Monica Cheesbrough.
Clinical chemistry by William J Marshall.
Reference books:
Medical Laboratory technology by Ramnik
Sood.
REASONS FOR ORDERING TESTS

Aid in diagnosis

Confirm diagnosis

Evaluate prognosis

Monitor therapy

Screen for a disease
SECTIONS OF THE LABORATORY
CLINICAL
PATHOLOGY
1. Clinical Chemistry



BUN
Cholesterol
FBS
2. Clinical Microscopy

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

Analysis of body fluids
Urin analysis
Fecal anaysis
Semen analysis
3. Microbiology
Cultures (sputum,
blood, urine)

4. Hematology
Biggest section
Includes CBC,coagulation,
PT, PTT
BLOOD BANK
Very critical section
Serology/Immunology
Bec. May have errors

Blood typing

Cross match

AB

Identification
Goes hand in hand with serology
and immunology
Tests done for

MALARIA

SYPHILIS

HIV

Cardiac and thyroid fxntest
II. ANATOMY PATHOLOGY
Histopathology
Submission of tissues for tests
LABORATORY SERVICES
Laboratory investigations of the patient.
 Laboratory aspects of detection and prevention of
diseases.
 Request
 System of analysis
 System for interpretation of results and timely
advice relevant to the urgency of the clinical
problem


FUNCTIONS OF A HOSPITAL LABORATORY
To meet the request for laboratory investigations
by maintaining adequate diagnostic facilities.
 To arrange for laboratory investigations from
referral laboratories if not available in the
premises.
 To provide professional advice on the
management of the patient.
 To monitor individual patients.
 To provide laboratory facilities for research
projects under taken by clinicians.
 To collaborate in development, study and control
of new methods of treatment.

To understand applied research on pathology
related problems.
 To arrange for the training of the medical and
paramedical staff.

NATURE OF REQUEST
STAT





Performed immediately
and by itself.
Run control and
standard
20-50% More expensive
TAT is shortened
Request is needed
Today
 Confusing
 Performed as soon as
possible, given
priority
 Based on “running
time”
Routine
 Done with the batch
 Wait for TAT stated
by laboratory
VALUES
REFERENCE VALUES
 Better term than
“normal value”
 Pulled value, usually
95%of population
 Vary in diff. hospitals
but not that far
SIGNIFICANT
VALUES
 Clinical decision should
be made if higher
or lower than reference
value
 Usually when 2x to 3x
CRITICAL VALUES




Needs immediate attention
“panic values”
Should call physician
Patient is at risk
REFERENCE VALUES
Not fixed for all
Should consider:






Age
Sex
Pregnancy
Diurnal Variation
Race
Blood type
ROUTINE EXAMINATIONS
ROUTINE ADMISSION TESTS
CBC, Urinalysis, Fecalysis
ROUTINE CHEMISTRIES
BUN, Creatinine, Glucose, Uric Acid, Cholesterol
Sometimes triglycerides
BASIC LAB EQUIPMENTS


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

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
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The Light Microscope.
Colorimeters and photometers
Water bath
Laboratory centrifuge
Balance
Cold incubators refrigerators
pH meters
Mixers
Ovens
De-ionizers
Safety cabinets.
Glassware and plasticware
SAMPLING
Pathologist should try to answer the question
which is imposed by the clinician.
 Correct specimen for requested test with
necessary information so that right test is carried
out And result is delivered to the requesting
clinician with the minimum of delay.
 Patient identification must be correct.

SPECIMEN TYPES
Venous blood serum or plasma.
 Arterial blood.
 Capillary blood
 Urine
 Feces
 Cerebrospinal fluid
 Sputum and sliva
 Tissue and cells
 Aspirates (pleural fluid, ascites, joint fluid,
intestinal (duodenal) fluid, pancreatic
pseudocysts.
 Calculi

BLOOD SPECIMENS


Serum
Plasma
Urine specimen
 Preservative may be added to prevent bacterial
growth or acid may be added to stabilize metabolites.
Other specimen types
Dangerous specimen
 Labelled as “dangerous specimen” yellow sticker.
 Similar label should be attached on the request form.
 HBV and HIV
SAMPLING ERRORS
Blood sampling techniques
 Prolonged stasis during venepuncture
 Insufficient specimen
 Errors in timing
 Incorrect specimen container
 In appropriate sampling site
 Incorrect sample storage.

LIPID CHEMISTRY AND
CARDIOVASCULAR PROFILE
Main lipids in the blood are the triglycerides and
cholesterol.(phospholipids, FFA)
 These are insoluble in the water.
 Transport in the blood is via
lipoproteins.(protein)
 4 major classes of lipoproteins.

Chylomicrons
 Very low density lipoproteins (VLDL)
 Low density lipoproteins (LDL)
 High density lipoproteins (HDL)

LIPOPROTEINS COMPOSITIONS
COMPOSITION OF LIPOPROTEINS
Class
Diamete
r (nm)
%
triacylglyc
%
%
erol
% protein
phospholipi
cholesterol
&
d
cholesterol
ester
HDL
5–15
33
30
29
4
LDL
18–28
25
50
21
8
IDL
25–50
18
29
22
31
VLDL
30–80
10
22
18
50
8
7
84
Chylomicr
100-1000 <2
ons
LIPOPROTEINS





Chylomicrons carry triglycerides ( dietary fat) from
the intestines to the liver, to skeletal muscle, and to adipose
tissue.
Very-low-density lipoproteins (VLDL) carry (newly synthesised
or endogenous) triglycerides from the liver to adipose tissue
and metabolized to LDL through IDL.
Intermediate-density lipoproteins (IDL) are intermediate
between VLDL and LDL. They are not usually detectable in
the blood.
Low-density lipoproteins (LDL) carry cholesterol from the liver
to cells of the body. LDLs are sometimes referred to as the "bad
cholesterol" lipoprotein.
High-density lipoproteins (HDL) collect cholesterol from the
body's tissues, and take it back to the liver. HDLs are
sometimes referred to as the "good cholesterol" lipoprotein.
LIPOPROTEIN METABOLISM
60% of plasma cholesterol is present in LDL, 25%
in HDL and small quantity in VLDL.
 Lipoprotein metabolism is controlled by their
protein component apolipoproteins.
 Apo A-1 in HDL and Apo B-100 in LDL are very
important ones.
 Lipoprotein (a) in also present in human
plasma. It is synthesized in the liver.
 Smaller but denser than LDL.
 Cholesterol esters are major lipids and it is an
independent risk factor for IHD.

LDL and VLDL are associated with premature
atherosclerosis.
 HDL high levels are negative risk factors for
IHD.
 HYPERLIPIDEMIA
 Coronary heart disease
 Acute pancreatitis
 Failure to thrive and weakness
 Cataract

Endothelial dysfunction
 Lpid accumulation.
 Migration of inflammatory cells into the arterial
wall.

Atherosclerosis and plaque formation
Plaque stability
SCAD (asymptomatic)
Chest pain at rest
(angina, non ST elevation MI, STEMI)
PATHOPHYSIOLOGY
Atherosclerotic plaque, rupture and thrombus
formation.
 Obstruction of coronary circulation.
 Necrosis of the heart tissue.
 Irreversible cardiac injury if occlusion is complete
for 15-20 mins.
 Starts from endocardium and spreads towards
epicardium.
 If full thickness of myocardium is involved then it
is transmural infarct.

PRECIPITATING FACTORS
Physical exertion
 After surgical operation
 Early in the morning (adrenergic activity,
fibrinogen level, platelet adhesiveness is
increased).
 In the winter months
 Emotional stress

DIAGNOSIS OF MI
Detection of rise and fall of cardiac biomarker
troponinT/I with one of the following:
 Symptoms of ischemia
 ECG changes
 Q wave

ECG CHANGES
CARDIAC PROFILE TEST


ENZYMES
 Creatinine Kinase –MB(CK-MB)
 Lactate Dehydrogenase(LDH 1 and 2)
 Aspartate Aminotransferase(AST)/Serum
Glutamate Oxaloacetate Transaminase(SGOT)
 Alanine Aminotransferase(ALT)/ Serum Pyruvate
Transaminase(SGPT)
LIPID PROFILE
 CHOLESTEROL
 TRIGLYCERIDE
 HDL
 LDL
PROTEINS
Myoglobin
 Troponins

CARDIAC PROFILE
Cardiac Enzymes
Cardiac Profile assesses the function of the heart’s
muscle and the increased level of enzymes following a
myocardial infarction. The cardiac enzymes include
the following:



Aspartate aminotransferase (AST)
Lactate dehydrogenase (LD)
Creatine Kinase (CK)
ASPARTATE AMINOTRANSFERASE
(AST) (SGOT)
found in all tissue, especially the heart, liver, and skeletal muscles
it catalyzes the transfer of the amino group of aspartic acid to alphaketoglutaric acid to form oxaloacetic acid and glutamic acid
Reaction catalyzed:
Amino group
Alpha-keto group
Oxaloacetate &
In aspartic acid
In alpha-ketoglutaric acid
glutamate
Considerations in AST assays
-Serum is the best specimen
-Hemolyzed samples must be avoided
-Alcohol lowers AST values
-Muscle trauma like intramuscular injections, exercise, or surgical operation
can significantly increase AST levels
CLINICAL SIGNIFICANCE

Myocardial infarction
In myocardial infarction, AST levels are usually 4-10
times the upper limit of normal
 These develop within 4-6 hours after the onset of
pain
 Peak on the 24th – 36th hour
 Usually normalize on the 4th or 5th day





Muscular dystrophy
Hepatocellular disorders
Skeletal muscle disorders
Acute pancreatitis
INCREASED LEVELS OF AST
Drug hepatoxicity
 Pulmonary infarction
 Pericarditis
 Acute hepatitis
 Skeletal muscle disorders

DECREASED LEVELS OF AST

Pregnant women
Falsely elevated results
 Bilirubin
 Aceto-acetatae
 N-acetyl compounds
 P-aminophenol
 Sulfathiozole
 Isoniazid
 Methyldopa
 L-dopa
 Ascorbic acid
LACTATE DEHYDROGENASE (LDH)
Catalyzes the reversible oxidation of lactate to
pyruvate
 Used to indicate AMI
 Is a cytoplasmic enzyme found in most cells of
the body, including the heart
 Not specific for the diagnosis of cardiac disease

DISTRIBUTION OF LD ISOENZYMES

LD1 and LD2 (HHHH, HHHM)
Fast moving fractions and are heat-stable
 Found mostly in the myocardium and erythrocytes
 Also found in the renal cortex


LD3 (HHMM)


Found in a number of tissues, predominantly in the white
blood cells and brain
LD4 and LD5 (HMMM, MMMM)
Slow moving and are heat labile
 Found mostly in the liver and skeletal muscle

CONSIDERATIONS IN LD ASSAYS
Red cells contain 150 times more LDH than
serum, therefore hemolysis must be avoided
 LDH has its poorest stability at 0°C

Clinical Significance
 In myocardial infarction, LD increases
3-12
hours after the onset of pain
 Peaks at 48-60 hours and remain elevated for 1014 days
 In MI, LD1 is higher than LD2, thus called
“flipped” LD pattern
FLIPPED
LDH
An inversion of the ratio of LD isoenzymes
LD1 and LD2; LD1 is a tetramer of 4 H–heart
subunits, and is the predominant cardiac LD
isoenzyme;
Normally the LD1 peak is less than that of the
LD2, a ratio that is inverted–flipped in 80% of
MIs within the first 48 hrs DiffDx. LD flips also
occur in renal infarcts, hemolysis,
hypothyroidism, and gastric CA
INCREASED LEVELS OF LD
Megaloblastic anemia
 Pulmonary infarction
 Granulocyte leukemia
 Hodgekin’s disease
 Hemolytic anemia
 Infectious mononucleosis
 Progressive muscular dystrophy (PMD)

CREATINE KINASE (CK)
Is a cytosolic enzyme involved in the transfer of
energy in muscle metabolism
 Catalyzes the reversible phosphorylation of
creatine by ATP
 -Is a dimer comprised of two subunits, resulting
in three CK isoenzymes

The B, or brain form
 The M, or muscle form

Three isoenzymes isolated after
electrophoresis:



CK-BB (CK1) isoenzyme
 Is of brain origin aand only found in the blood if the bloodbrain barrier has been breached
CK-MM (CK3) isoenzyme
 Accounts for most of the CK activity in skeletal muscle
CK-MB (CK2) isoenzyme
 Has the most specificity for cardiac muscle
 It accounts for only 3-20% of total CK activity in the heart
 Is a valuable tool for the diagnosis of AMI because of its
relatively high specificity for cardiac injury
 Established as the benchmark and gold standard for other
cardiac markers
Considerations in CK assays
CK is light sensitive and anticoagulants like
oxalates and fluorides inhibit its action
 CK in serum is very unstable and rapidly loss
during storage
 Stored specimens are not used since it contains
cellular products and intermediate like adenylate
kinase, ATP and G-6-Phosphate which affect the
assay
 Exercise and intramuscular injections causes CK
elevations

Clinical Significance
-In myocardial infarction, CK will rise 4-6 hours
after the onset of pain
 -Peaks at 18-30 hours and returns to normal on
the third day
 -CK is the most specific indicator for myocardial
infarction (MI)

Raised levels of CK
 Progressive muscular dystrophy
 Polymyositis
 Acute psychosis
 Alcoholic myopathy
 Delirium tremens
 Hypothyroidism
 Malignant hyperthermia
 Acute cerebrovascular disease
 Trichinosis and dermatomyositis
Normal Value:
 a. Male – 25-90 IU/mL
 b. Female – 10-70 IU/mL
CHOLESTEROL
Normal values: range varies according to age
 Total Cholesterol: 150-250mg%
 Cholesterol esters: 60-75% of the total cholesterol

CHOLESTEROL IS ADVISED IF YOU
 have been diagnosed with coronary heart disease,
stroke or mini-stroke (TIA) or peripheral arterial
disease (PAD)
 are over 40
 have a family history of early cardiovascular disease
 have a close family member with cholesterol-related
condition
 are overweight
 have high blood pressure, diabetes or a health
condition that can increase cholesterol levels, such as an
underactive thyroid
FACTORS LEADING TO RAISED
CHOLESTEROL



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
an unhealthy diet: some foods already contain
cholesterol (known as dietary cholesterol) but it is the
amount of saturated fat in your diet which is more
important
smoking: a chemical found in cigarettes called
acrolein stops HDL from transporting LDL to the
liver, leading to narrowing of the arteries
(atherosclerosis)
having diabetes or high blood pressure(hypertension)
having a family history of stroke or heart disease
There is also an inherited condition known as familial
hypercholesterolaemia (FH). This can cause high
cholesterol even in someone who eats healthy diet.
TRIGLYCERIDES




Ester derived from glycerol and three fatty acids.
Main lipids in the blood and important energy substrate.
Insoluble in water.
Hypertriglyceridemia
Not an important risk facotr for coronary artery disease.
 It can cause pancreatitis when severe.

Both hypertriglyceridemia and hypercholesterolemia are
associated with various types of cutaneous fat deposition and
xanthomatas.
Hypertension


Very common clinical problem. Usually essential type
meaning that have no identifiable cause.
Investigations for treatable causes like endocrine is
necessary.
HYPERLIPIDEMIAS
LIVER
Anatomy of liver
LIVER HISTOLOGY
I.
TESTS BASED ON EXCRETORY
FUNCTIONS
LABORATORY RESULTS
II.
TESTS DUE TO DETOXIFICATION
TESTS B/O SYNTHETIC FUNCTION
Liver is the main source of synthesis of
 Plasma proteins

Albumin
 Globulin


Blood clotting factors
Prothrombin
 Factors V, VII, and X

SERUM ALBUMIN

3.5- 5.5 gm/dl
SERUM GLOBULIN

2 -3.5 gm/dl
TOTAL PROTEINS

6-8 gm/dl
Albumin/ Globulin ratio
 1.2:1 – 2.5: 1
Prothrombin time
TESTS B/O METABOLIC FUNCTIONS
SERUM TRANSAMINASES
SERUM ALKALINE PHOSPHATASES
REFERENCE RANGE
ALT ( upto 42 U/L)
 AST (0-37 U/L)
 ALP (65-306 U/L) raised in obstructive jaundice.

OTHER ENZYMES
GGT (11-60 u/l)
 5- NUCLEOTIDASE (2-17u/L)
 LDH (180-360 u/l)

pathogenesis
Different cells have different enzymes inside them,
depending on the function of the cell. Liver cells
happen to have lots of AST, ALT, and GGTP inside
them. When cells die or are damaged, the enzymes
leak out causing the blood level of these enzymes to
rise; that is why the levels of these enzymes in the
blood are considered
good indicators of liver cell damage. ALT is more
specific for liver disease than AST because AST is
found in more types of cell (e.g. heart, intestine,
muscle). The AST, for instance, will rise after a heart
attack or bruised kidney. GGTP and AP are said to be
more specific for evaluating biliary disease since they
are made in bile duct cells. In liver disease caused by
excess alcohol ingestion, the AST tends to exceed the
ALT, while the reverse is true to for viral hepatitis.
However, this particular generalization is often
wrong. There are several things to remember:
GGT (OR GGTP)
Gamma Glutamyl Transpeptidase. This enzyme
level is elevated in case of liver disorders. In
contrast to the alkaline phosphatase, the GGT
tends not to be elevated in diseases of bone,
placenta, or intestine
PROTHROMBIN TIME
good correlation between abnormalities in
prothrombin time and the degree of liver dysfunction.
 Expressed in seconds and compared to a normal
control patient's blood
SPECIALIZED TESTS
 serum iron,
 the percent of iron saturated in blood,
 the storage protein ferritin for hemochromatosis.
 accumulation of copper in the liver in wilson disease.

RENAL PANEL
Creatinine
 Calcium
 Sodium
 Chloride
 Carbon dioxide
 Albumin
 Blood urea nitrogen (BUN)
 Protein
 Phosphorus
 Glucose
 Potassium

Glucose
 Potassium
 Phosphorous
 Sodium
 Albumin
 BUN
 Creatinine
 BUN/Creatinine Ratio
 Calcium
 Chloride
 Carbon Dioxide (CO2), Total

BONE METABOLISM
Bone is constantly remodelling
 Bone resorption= bone formation
 Why remodelling is necessary?

To withstand changing environment
 To cope with workload
 To repair damage caused by recurrent microtraumas
BONE METABOLISM
Osteoclasts and Osteoblasts
Osteocytes\
Encased osteoblasts which are connected to each other
by long cellular processes forming a network
connected by gap junctions.
