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Chapter 44
Specialty Laboratory Tests
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Urine Pregnancy Tests
• When used
– When pregnancy suspected
– To rule out pregnancy
• Before prescribing birth control pills, radiographic
studies, certain antibiotics, other drugs
– For females who are to undergo surgery
• Based on detection of human chorionic
gonadotropin (hCG)
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Urine Pregnancy Tests
• Commercial/home pregnancy tests
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Variety available
Easy to perform and interpret
Give rapid results
OTC products
Should be confirmed by laboratory test using
appropriate quality controls
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or duplicated, or posted to a publicly accessible website, in whole or in part.
False/Positive Test
Pregnancy Results
• Positive reaction to any pregnancy test
does not necessarily indicate normal
pregnancy
• Detection of hCG can also indicate
abnormal conditions
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or duplicated, or posted to a publicly accessible website, in whole or in part.
False/Positive Test
Pregnancy Results
• Quality control
– Kits must be stored and used at temperature
directed by manufacturer
– Built-in control
– Expiration date
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
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Contagious disease
May have vague clinical symptoms
Can mimic other diseases
Serologic tests basis for early diagnosis
Commonly called “mono” or “kissing
disease”
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• Result of infection of lymphocytes by
Epstein-Barr virus (EBV)
• After primary infection, virus establishes
lifelong latency
• EBV implicated in other diseases
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• Transmission of EBV
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By saliva
Sharing of drinking glasses
Blood transfusion
Close social groups
Importance of hand washing
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• Symptoms of IM
– Seen most often in children and young adults
– Incubation of 7–14 days average
– Younger children usually asymptomatic or
manifest minor symptoms
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• Symptoms of IM
– Classic symptoms occur when primary infection
delayed until second decade of life
– Fever, swollen glands, headache, malaise, chest
pain, cough, tonsillitis, rash, swollen lymph nodes,
swollen spleen
– Symptoms last average of 2–4 weeks
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• Treatment of IM
– No effective drugs available
– Primarily supportive
– Vaccine not yet available
• Diagnosis of IM
– Blood and serology test results
– Patient’s symptoms
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• Diagnosis of IM
– Blood test for IM
• Includes WBC count
• Evaluation of patient’s lymphocytes
– Serological test for IM
• Detection of heterophile antibodies
• Combined with blood tests and patient symptoms
• Positive after first week of illness
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Infectious Mononucleosis
• CLIA waived IM tests
– Test kits: all necessary reagents, materials,
controls
• Prothrombin time
– Protime, PT, international normalized ratio (INR)
– Test for blood’s clotting ability
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Typing
• Based on
presence or
absence of
antigens on
surface of RBCs
• Immunoglobulins
(Ig)
• Hemagglutination
reactions (ABO
blood group; Rh
factor)
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Typing
• ABO blood typing
– Determined by presence or absence of antigens A
and B
– All people have one of four blood group
categories: A, B, AB, O
– Determined by slide or tube method
– “Blood cross and match” test
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Typing
• Rh blood typing
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Routinely performed together with ABO typing
Named for rhesus monkey
Rh factor found on surface of RBC
Rh positive and Rh negative
85% of North Americans Rh positive
15% Rh-negative
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Typing
• Rh blood typing
– Can develop antibodies
– Importance of knowing Rh blood type
• For transfusions
• For childbirth
• Hemolytic disease (HDN): maternal hemolysis of fetal
RBCs
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Semen Analysis
• When performed
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To determine sperm cell count
As part of complete fertility workup
To evaluate effectiveness of vasectomy
To determine paternity
To substantiate rape cases
• Reference values for semen analysis
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Semen Analysis
• Semen composition
– Composite solution produced by testes
– Spermatozoa suspended in seminal plasma
– Variation in composition between different portions
of fluid as ejaculated
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Semen Analysis
• Altering factors in semen analysis
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Several drugs/chemicals
Orchitis
Testicular atrophy
Testicular failure
Obstruction of vas deferens
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Semen Analysis
• Altering factors in semen analysis
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Cigarette smoking
Coffee drinking
Fever
Aspermia (no sperm)
Oligospermia (low sperm count)
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Phenylketonuria (PKU) Test
• Inherited condition
• Baby cannot metabolize protein
properly
• Phenylalanine-restricted diet will
prevent mental retardation; will not cure
underlying condition
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Phenylketonuria (PKU) Test
• Routine screening of newborns for PKU
mandatory in all states
• Tests for excess phenylalanine in blood or
urine
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Phenylketonuria (PKU) Test
• Blood testing for PKU
– Guthrie screening test
– Transfer from capillary heelstick puncture site to PKU filter
card
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Phenylketonuria (PKU) Test
• Blood testing for PKU
– Factors that may influence the Guthrie test
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Feeding problems
Failure to ingest sufficient phenylalanine
Premature infants
Drugs taken by mother or infant
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Morbidity on the rise
• Advisory Council for Elimination of
Tuberculosis recommends screening
high-risk groups
• Cause of TB
– Mycobacterium tuberculosis
– Ziehl-Nielson method of identification
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Resistance in mycobacteria
– Tolerance for drying and many disinfectants
– To most antibiotics
– Overcoming bacterial resistance patients take two
or three drugs for period of 6 to 9 months
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Transmission of infectious TB
– Highly contagious
– Most new cases (75%) occur by inhalation of
cough-produced airborne droplets from
symptomatic or asymptomatic persons
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Transmission of infectious TB
– Conditions that contribute to transmission
• Poverty
• Poor nutrition
• Crowded conditions (mental health hospitals and
prisons)
• Related to increase in AIDS cases
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Diagnosis of TB
– Active TB
• Serious and contagious condition
• Isolation and aggressive treatment with several drugs
over several months
– Latent or inactive TB
• Can live in body without causing illness
• With illness or injury, can become active
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Diagnosis of TB
– Patients exhibiting positive or questionable
purified protein derivative (PPD) reaction should
have chest x-ray and tuberculin skin test (TST) or
sputum sample
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• Screening for TB:
skin testing
– May be part of routine
examination or
prerequisite for school
or employment
– Use tuberculin (PPD)
– Reading the results
Mantoux test >>
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Tuberculosis
• The Mantoux test
– PPD injected intradermally using 1 mL tuberculin
syringe
– Care must be taken to inject PPD so that wheal
forms
– Draw exactly 0.1 mL of PPD; too much or too little
will lead to erroneous test results
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Glucose
• Glucose serves as energy source for
body
• Tests for blood glucose levels screen
for carbohydrate disorders
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Hypoglycemia (low blood glucose level)
Hyperglycemia (high blood glucose level)
Diabetes mellitus
Liver dysfunction
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Glucose
• Fasting blood glucose
– Used to screen for diabetes mellitus, Cushing’s
syndrome, acute stress response
– Reference glucose values
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Glucose
• Two-hour postprandial blood glucose
– Performed after eating
– Used to screen for diabetes and to monitor insulin
dosage
– Glucola®
– Blood sample collected
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Glucose
• Glucose tolerance test (GTT)
– Follows fasting urine and blood samples
– Patient consumes glucose test solution
– Blood and urine samples collected at timed
intervals after ingestion
– Helps determine ability to deal with increased
glucose
– Symptoms
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Glucose
• Automated methods of glucose analysis
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HemoCue® blood glucose system
Handheld glucose meters
Glucose controls
Use consistent proper specimen collection and
testing technique to avoid variations in results
– Reflectance photometry analyzers
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Glucose
• Testing panels
– Glucose testing part of general or specific
chemistry panel test
• Glycosylated hemoglobin
– Stable molecule formed when sugar and
hemoglobin bind on the RBC
– Increased finding indicates poor glucose control
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Cholesterol, Lipids, and
Systemic Inflammation
• Cholesterol
– Fatty compound essential for many vital life
functions
– Normal constituent of blood
– Excess linked to coronary artery disease
– Fats should not make more than 30% of total
intake of calories daily
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Cholesterol, Lipids, and
Systemic Inflammation
• Chemistry of cholesterol
– Reference values for total blood cholesterol
– Consists of carbon, hydrogen, oxygen
– Saturated fatty acid
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Cholesterol, Lipids, and
Systemic Inflammation
• Functions of cholesterol
– Cells use cholesterol to manufacture steroid
hormones
– Important component of bile and cellular
membranes
– May accumulate in body and reach dangerous
levels
– Take in cholesterol when eating meat, eggs, dairy
products
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Cholesterol, Lipids, and
Systemic Inflammation
• Lipoproteins and cholesterol transport
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High-density lipoprotein (HDL)
Low-density lipoprotein (LDL)
Reference ranges for HDL and LDL cholesterol
Cholesterol screening helps identify patients at
high risk for heart disease
– Cholesterol testing part of lipid profile
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.
Cholesterol, Lipids, and
Systemic Inflammation
• Triglycerides
– Type of lipid found in blood that serves as source
of energy
– Liver converts fatty acids and glycerol from diet
– Adipose tissue (fat)
– Increased concentrations associated with
increased risk for coronary and vascular disease
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Inflammation
• Systemic inflammation predominant
cause of heart disease; causes
cholesterol to accumulate in arteries
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Bacteria
Viruses
Toxins
Certain foods (over-processed, pre-packaged,
high in omega-6 acids)
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Chemistry Tests
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Alanine aminotransferase (ALT)
Albumin
Alkaline phosphatase (ALP)
Aspartate aminotransferase (AST)
Bilirubin, total and direct
Blood urea nitrogen test (BUN)
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Chemistry Tests
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Calcium
Chloride
Carbon dioxide (CO2)
Creatinine
Gamma glutamyltransferase (GGT)
Lactate dehydrogenase (LDH)
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or duplicated, or posted to a publicly accessible website, in whole or in part.
Blood Chemistry Tests
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Phosphorus (phosphate)
Potassium (K)
Sodium
Total protein
Uric acid
© 2014 Cengage Learning. All Rights Reserved. May not be scanned, copied
or duplicated, or posted to a publicly accessible website, in whole or in part.