Welcome to the Clinical
Laboratory
CLINICAL CHEMISTRY
Clinical Chemistry
 Clinical chemistry is the department in the lab where
pure chemistry meets up with disease and clinical
diagnosis. An example would be electrolyte levels in
blood.
 Clinical chemistry is most likely the largest
department in any laboratory as well as the most
automated.
 Clinical chemistry measures levels of chemical
components in body fluids. These chemicals are
called biochemicals.
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Types of Measurements in Chemistry
 Qualitative measurement relies on words (some,
many, none, pale) to tell us quality.
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The liver enzymes are high.
 Quantitative measurement relies primarily on
numbers as the main unit of analysis.
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The blood glucose is 100mg/ml.
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 Biochemicals measured may include blood glucose,
electrolytes, enzymes, hormones, lipids (fats), other
metabolic substances, and proteins.
 The results of these measurements is quantitative,
meaning there will be numbers involved stating “how
much.”
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We’ve mentioned this before in another PowerPoint, but,
would the doctor have a more accurate picture of health with
an answer like, “an elevated BUN” or “the BUN result is
2.4mg/dl”?
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Examples of Measuring Biochemicals:
 Blood glucose, or blood sugar levels indicate how the
body handles glucose.
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Measuring glucose levels after fasting can help diagnose
diabetes or hypoglycemia (low blood sugar).
 Cardiac enzyme levels indicate the health of heart
muscles.
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Measuring cardiac enzymes can help the doctor determine if
the patient has had a heart attack, when the episode occurred
and how severe it was.
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Types of Specimens used in Clinical Chemistry
 Tests in clinical chemistry are performed primarily
on serum, plasma, urine and other body fluids.
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Serum is the yellow watery part of blood that is left after blood
has clotted and all blood cells have been removed.
Plasma is in essence the same as serum, but is in
blood which hasn’t clotting. Plasma is obtained by
centrifugation before clotting occurs.
Both look similar and can easily be visually
confused.
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Clinical Chemistry is Sometimes Called Analytical
Chemistry
 An analyte is the chemical in the blood that we want
to test for.
 A solvent is the liquid in which the analyte is
dissolved (serum, plasma, urine, spinal fluid or CSF).
 Analyte + Solvent = Solution.
 The solution being tested in chemistry is either
serum, plasma, or other body fluid in which an
analyte is dissolved.
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Reagents used in Clinical Chemistry
 Reagents -substances that are employed to produce a
chemical reaction when coupled with other substances.
 Preparation of any reagent, control, standard or chemical
requires precision and accuracy
 Depending on the instrumentation, reagents come in
several forms: liquid, dry, cartridge, strip.
 Any reagent that is prepared must be labeled with
date/time of preparation, concentration.
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Standards - Different Than Reagents
 The greatest portion of chemistry testing is
quantitative analysis - testing results in a
number.
qualitative testing results in positive/negative,
plus/minus, yes/no results. (the 'n' in quantitative
means 'number'.)
Standards are purified chemicals that have known and
exact values. They are used to calibrate instruments.
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Ordering Tests in Clinical Chemistry
 Large chemistry labs receive orders for hundreds of
different tests
 But few labs do all the tests ordered
 Tests not done in these smaller labs are sent to
reference labs to be run in much larger batches
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Ordering Tests in Chemistry
 Tests that are done right in the hospital lab are
sometimes categorized as general or routine tests.
 These tests can be ordered individually as single
tests or they are categorized as panels. Panels are
sets of tests grouped to look at problems in body
systems. These are the same systems you studied in
A&P.
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Two Most General Screening Panels
 Basic Metabolic Panel: serves as an initial broad
medical screening tool of kidney,
liver function, and electrolyte and fluid balance
 Comprehensive Metabolic Panel: same as BMP, but
more tests are included, maybe thyroid, calcium or
alkaline phosphatase.
These tests are used to screen general health of a
patient. They aren’t used to follow the course of
disease and treatment.
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Panels of Tests in Chemistry
 As you can see, these panels are diagnostic tools for
many different body systems.
Problems with the
renal system would
an example of a
finding of these panels.
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Electrolyte Panel
 Electrolyte Panel: may include sodium, potassium,
chloride, CO2. Measuring electrolytes can
specifically indicate certain metabolic and kidney
disorders.
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Kidneys help balance acids and bases in the body. While it may
be helpful to the doctor to know the specific CO2 level of a
patient, the other tests in an electrolyte panel work together to
give a picture of acid-base balance and hydration status of the
patient. Can you see why electrolytes are affected by kidney
function?
Electrolytes (cont.)
 And as you might guess from their name, electrolytes are
electrically charged, which means that they can conduct electrical
impulses. The body needs electrical impulses to make muscle
cells contract. So, severe imbalance of electrolytes is a very
dangerous thing. A common cause of such a degree of electrolyte
imbalance is dehydration. (Drink your water!)
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Kidney Function Panel
 Kidney Function Panel: BUN* and Creatinine to
assess function of kidneys. Both are waste products
excreted by the kidneys.
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If a BUN test reveals that your urea nitrogen levels are higher
than normal, it probably indicates that your kidneys aren't
working properly. The same is true for the creatinine test –
high levels show poor kidney function.
BUN* is actually an acronym for Blood Urea Nitrogen. It isn’t pronounced bun, like hamburger
bun, but B.U.N.
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Lipid Panel
 Lipid Panel: lipids are fats in the body. This panel
gives a profile of Total Cholesterol, HDL-cholesterol
(good cholesterol), LDL-cholesterol (bad
cholesterol), and triglycerides (fats).
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Lippoproteins transport cholesterol, triglycerides, HDL, LDL
and VLDL, which are predictors of heart disease. A patient
can feel perfectly healthy but have a high risk for cardiac
problems if they have high levels of some of these lipoproteins.
HDL carries cholesterol from the tissues to the liver to be
excreted. So high levels of HDL are good.
LDL carries cholesterol too, but deposits the cholesterol in
blood vessels. This increases the risk for strokes and heart
attacks.
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Plaque deposits
 You can see why it’s good to know lipid levels when
you see what plaque does to a vessel. Which
cholesterol type deposits plaque in the vessels?
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Thyroid Panel
 Thyroid Panel: to help evaluate thyroid function and
diagnose thyroid disease.
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Commonly includes TSH, T4, T3
 The thyroid gland is an important organ that
regulates body metabolism. It is located in the front of
the neck just below the voice box.
It secretes two main thyroid hormones – thyroxine (T4)
and triiodothyronine (T3).
 These hormones allow the body to use energy. If you have
too little of these hormones, you have not used the possible
energy and are tired.
 So, if the mechanisms are working badly, patient is feeling
tired, they could be suffering from hypothyroidism.
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The Thyroid and Pituatary Glands
 Together these two glands work to regulate
metabolism. So, if the patient is always tired, a
Thyroid Panel may be ordered to assess hormone
levels.
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Enzyme Panels
 Enzymes Panel – enzymes are in all cells. Enzymes
are released into the blood by organs that are
damaged or diseased. The type of enzyme released
can indicate which organ is affected; heart, liver,
pancreas, even bone.
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There are Cardiac Enzyme Panels, Liver Enzyme Panels, etc.,
which are measuring the amount of different enzymes released
by the particular organ being investigated.
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Example of Diagnosis Using Enzyme Testing
 Enzymes tested are often called biomarkers
 When determining if chest pain and related
symptoms are due to heart burn or heart attack,
biomarkers are measured
 Acute myocardial infarction (AMI), also known as a
heart attack, is defined as the death or necrosis of
myocardial cells due to prolonged ischemia, often the
result of a sudden or severe blockage of blood flow to
the heart.
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Example of Diagnosis - Cardiac Enzymes
 The diagnosis of cardiac disease and injury is based
on a clinical picture that includes physical exam,
medical history, ECG, and laboratory testing,
including cardiac biomarker monitoring.
 Levels of these cardiac
biomarkers are measured at
timed intervals. A rise in level
of the enzyme indicates
damage has occurred.
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Beyond Panels to Special or Esoteric Chemistries
 Endocrinology: analysis of hormones and diagnosis
of endocrine disorders
 Toxicology: the study of drugs of abuse and other
chemicals
 Therapeutic Drug Monitoring: measurement of
therapeutic medications blood levels to optimize
dosage
 Electrophoresis: Protein studies
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Automation in Clinical Chemistry
 Even as late as 1960 most tests performed in the lab
were done manually. Reagents were made by the
technologists, tests were performed usually singly
when needed.
 Slowly at first, automation become the driving force
within the lab yielding better, faster, improved
testing.
 Most current laboratories are now highly automated
to accommodate the high workload typical of a
hospital laboratory. Tests performed are closely
monitored and quality controlled.
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Common Benefits of Automation
Also True for Clinical Chemistry
 Increased number of tests performed by one technologist
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in a given time period. Labor costs decrease.
Minimized variation in results between technologists due
to slight variations in technique.
Smaller amounts of sample/reagents.
Increased walk-away capabilities, more multi-tasking for
staff
Increased variety of techniques/tests being offered;
improved patient care as a result
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Testing by Manual Methods
 Manual means making the reagents and performing
the test by hand.
 Definitely slow
 Definitely labor intensive
 Often not precise
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Automated Chemistry Lab
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Automation in the Clinical Chemistry Lab
 Automated analyzers merely incorporate the
methods previously used in manual methods for
chemical analysis.
 Students in Med Tech or MLT programs learn these
manual methods to gain deeper understanding of the
automated instruments they will be using in the labs
they work in.
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Types of Manual Methods Used in Automation
 Spectrophotometer
 Electrophoresis
This automated instrument
uses all the methods
on the right.
 Ion Selective Electrode
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Spectrophotometry
 Spectrophotometry– analytical techniques to
measure the light absorbed (or transmitted) by a
colored solution at a particular wavelength;
dependent upon two things - color and intensity
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Example: An automated chemistry analyzer adds reagent
(colored solution) to specimen (containing the chemical to be
measured) and with spectrophotometry, measures
concentration of color. This tells us how much chemical is in
the specimen (ex. how high the glucose is.)
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Electrochemistry
 Electrochemistry - study of chemical reactions
occurring because of the flow or presence of
electrons between two dissimilar substances;
employs current and electrical reaction.

Example: Electrophoresis– process of measuring migration of
charged solutes/particles (usually proteins) in an electrical
field. Sometimes this is done by automated
electrophoresis sometimes the process is
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Ion Selective Electrode
 Ion Selective Electrode (ISE)- potentiometric
method measures movement of electrical, free ions.
Common measurement for sodium (Na), potassium
(K), and chloride (Cl).
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Example: analyzing electrolyte levels
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Or, the most common example in all labs is the pH Meter
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Mass Spectrophotometry
 Simply put, mass spectrophotometry identifies the masses of the
molecules making up a sample of material. This isn’t a kicked up
spectrophotometer – it works differently.
 It is used for determining the elemental composition of a sample,
and for clarifying the chemical structures of molecules.
 Often used in toxicology
 Example: A new innovation in mass spec is a portable instrument
which can measure chemicals in the environment (on the street)
giving quick results. Can you imagine the possibilities of using such
an instrument to keep the population safe?
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One Next to Last Thought
 All the automated instruments in the clinical lab, and
particularly in chemistry, require maintenance and
repair. People who do this type of repair are often
MLTs or MTs who enjoy tinkering with things.
Instrument repair is a lucrative job!
Review Questions
 What type of specimens are used for testing in
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chemistry?
Define analyte and solvent.
What are standards used for in chemistry?
Name two types of manual testing that has been
upgraded and is used in automation.
Panels test systems. True or false
If enzymes are found in all cells, why do we assay for high
levels?
What tests in chemistry will indicate that the patient is
dehydrated?