Lecture 4: Interpretation of Clinical Lab Values Flashcards
___: substances whose chemical constituents are being identified and measured
Analytes
Lab assays to measure analyte level usually use ___ prepared from whole blood drawn
serum
____: the watery acellular portion of blood separated by centrifugation of whole blood in the presence of anticoagulant
Plasma
What type of solution is plasma? serum?
plasma: physiological solution
serum: non-physiological solution
____: liquid remaining after centrifugation of whole blood that has been allowed to clot
Serum
Major advantage of serum?
There are no additives required to prevent clotting
True or False: Careless handling of serum may result in RBC lysis
True
True or False: There is a small possibility of false positives with serum
True
Most diagnostically important enzymes have _____ functions and do not normally function in ___.
intracellular; blood
What are two reasons why blood from normal healthy individuals may contain enzymes?
- Active secretion (i.e., coagulation precursors such as prothrombin)
- Release from cells at LOW LEVELS during normal cell turnover.
True or False: In healthy individuals blood enzyme levels are fairly constant – equilibrium between release and removal
True
Where do most enzymes function?
In cells
True or False: Disease or exposures to drugs, microbes, can cause damage to cell membranes (cell necrosis) and lead intracellular enzymes to be released into the blood, causing elevated blood enzyme concentrations
True
True or False: Enzymes in blood due to cellular damage function physiologically
False - Enzymes in blood due to cellular damage function no longer function physiologically
True or False: Detection of elevated enzyme levels can help to: 1) make/confirm dx; 2) develop prognosis, 3) monitor response to drug therapy
True
Two clinical reasons for elevated enzymes in blood?
1) Basal (normal) levels
-normal cellular turnover
2) Pathologies, drugs
-can cause enzyme levels greater than (or sometimes less than) basal levels
1) Which of these enzymes is the MOST specific test?
2) Which of these enzymes is the LEAST specific test?
3) How might you improve diagnostic specificity?
1) ALT
2) LDH
3) Panels/profiles/isoforms
True or False:
Serum chemistry profiles are generated for patients to:
1) assess health status
2) provide baseline levels
3) monitor response to treatment, etc.
True
____: Series or panel of 8 chemical blood tests that assess fluid and electrolyte status, kidney function, blood sugar levels (Diabetes), malnutrition and
response to various medications and other therapies
Basic Metabolic Panel/Chem 7
True or False: A BMP may identify acute problems involving kidney, diabetic shock, respiratory
distress and congestive heart failure
True
What 8 chemical blood tests are done for a BMP?
-Serum Sodium
-Serum Potassium
-Serum Chloride
-Serum Calcium
-CO2
-Blood Urea Nitrogen (BUN)
-Creatinine
-Glucose
____: A panel of 14 chemical blood tests that adds assessment of liver function to the BMP.
CMP (Chem 12)
True or False: A CMP is used as routine test during physical exam or to monitor chronic conditions such as hypertension or diabetes or to monitor response to a drug regimen
that may have kidney- or liver-related adverse reactions
True
What 14 chemical blood tests are looked at in a CMP?
Renal Profile?
Liver Profile?
Muscle Profile?
The Comprehensive Metabolic Panel includes the
Basic Metabolic Panel tests and also assesses which
of the following organs?
A. Heart
B. Pancreas
C. Liver
D. Brain
C. Liver
____: urea is a waste product of protein digestion; indicates kidney dysfunction
BUN (blood urea nitrogen)
___: waste product of muscle contraction cleared by kidneys; indicates kidney dysfunction.
Creatine
What does it mean if BUN/Creatinine ratio is >10:1 to 20:1?
Indicates poor blood flow to kidneys (i.e., congestive heart failure)
_____: waste product of purine breakdown cleared by the kidneys; indicates hyperuricemia/gout and kidney disease
Uric Acid
___, ___, and ___ assess biliary tract damage - cholestasis
ALK/ALP, GGT, 5’ NT
____ assesses chronic decrease vs. acute (normal) liver damage
Albumin
___, ____, and ___ assess hepatocellular damage
ALT, AST, and LDH
True or False: Bilirubin (T-, D- and I-BIL) assesses heme degradation product diagnostic for liver function, hemolytic anemias
True
Where is AST expressed?
AST: skeletal/cardiac muscle, liver
____ is a non-specific test for muscle and heart damage
LDH
___ is required for muscle cell function; after heart attack, strenuous exercise, muscle injury
Creatine kinase
What 4 enzyme tests are used to evaluate pancreatic function (i.e., pancreatitis):
1) amylase
2) lipase
3) lipase:amylase ratio – possible differentiation of alcoholic vs. non-alcoholic acute pancreatitis
4) trypsinogen/Trypsin
True or False: Prostate-specific antigen (PSA) – screening test for prostate cancer
True
Which elevated serum test result paired with elevated AST levels would be the most specific diagnostic for liver disease?
Which analyte is most likely to be elevated in a patient’s serum following a heart attack?
A. CK
B. BUN
C. Creatinine
D. Amylase
A. CK
Elevated CK following a heart attack will most likely accompany elevated..
A. Albumin
B. BUN
C. AST
D. Lipase
C. AST
____: the ability of test to actually measure what it claims to measure
____: the ability to reproducibly obtain the same result on the same patient sample.
Accuracy
Precision
True or False: Accuracy is the sum of true positive results and true negative results divided by the total number of samples
tested.
True
What type of distribution defines the reference range?
Gaussian Distribution
In a normal population with Gaussian distribution ___% of individuals will be ±1 SD and ___% ±2 SD.
68%; 95%
The reference range is the range of
values within__ SD of the mean,
which covers __ % of healthy
individuals
2 ; 95%
True or False: Average total cholesterol in the U.S. is greater than the recommended levels (< 200 mg/dl) for decreased risk of heart disease,
which is determined epidemiologically.
True
What 4 factors influence reference range?
1) Interlaboratory variation
2) “Normal” reference population is not really “normal”
3) Physiologic variation (age, biological sex, ethnicity, time of day, etc.)
4) Skewed “non-random” distribution of analyte values in reference population
Isoenzymes or Isozymes are distinct variant forms of an enzyme. All isozymes of an enzyme catalyze the same ___ but differ slightly in what three ways?
reaction
1) amino acid composition
2) Cell- and tissue-type in which they function
3) Timing of expression
True or False: LDH is a isoenzyme
True
_____: catalyzes the reversible formation of lactate from pyruvate (pyruvate from lactate in the liver)
Lactate dehydrogenase (LDH)
LDH is a ____(4 subunits) composed of various combinations of __ and __ subunits
tetramer
H; M
True or False: LDH is a highly non-specific test in isolation (heart, liver, lungs, kidneys, sk.muscle, RBCs and lymphocytes); however, isozyme-specific tests are much more specific.
True
If LDH-1:LDH-2 >1, what does this indicate?
If LDH-5:LDH-4 > 1, what does this indicate?
HEART damage
LIVER damage
___ Isoenzymes are dimers composed of 2 __ monomers, 2 __ monomers, or one of each
CK Isoenzymes
B-monomers; M-monomers
CK-BB (CK-1) is found in greatest abundance in the ___
Diagnostic value = ____
Brain
CNS damage
CK-MB (CK-2) is found in greatest abundance in the ____
Diagnostic value = _____
myocardium
Diagnostic value = Acute myocardial infarction (AMI)
CK-MM (CK-3) is found in greatest abundance in the ____ muscle
Diagnostic value = ____
skeletal muscle
Diagnostic value = skeletal muscle damage
True or False: LDH and CK Isozymes in Heart Disease
True
______heart attacks cause cardiomyocyte damage and release of cardiac enzymes into the blood.
Acute Myocardial Infarctions (AMI)
Combination of ____ and ___ isozymes along with ___ and ___ are diagnostic for AMI
CK-MB; LDH-1; Troponins; Myoglobins
Cardiac troponin exists as a complex of protein subunits:
___, ____, and ____
TnI, TnT, and TnC
True or False: Troponin regulates Ca2+-mediated actin-myosin interactions during cardiac muscle contraction.
True
Which LDH isozyme is the most specific diagnostic test for Liver damage?
A. LDH-1
B. LDH-2
C. LDH-3
D. LDH-4
E. LDH-5
E. LDH-5
