Lecture 4: Interpretation of Clinical Lab Values

Question 1

___: substances whose chemical constituents are being identified and measured

Answer 1

Analytes

Question 2

Lab assays to measure analyte level usually use ___ prepared from whole blood drawn

Answer 2

serum

Question 3

____: the watery acellular portion of blood separated by centrifugation of whole blood in the presence of anticoagulant

Answer 3

Plasma

Question 4

What type of solution is plasma? serum?

Answer 4

plasma: physiological solution
serum: non-physiological solution

Question 5

____: liquid remaining after centrifugation of whole blood that has been allowed to clot

Answer 5

Serum

Question 6

Major advantage of serum?

Answer 6

There are no additives required to prevent clotting

Question 7

True or False: Careless handling of serum may result in RBC lysis

Answer 7

True

Question 8

True or False: There is a small possibility of false positives with serum

Answer 8

True

Question 9

Answer 9

Question 10

Most diagnostically important enzymes have _____ functions and do not normally function in ___.

Answer 10

intracellular; blood

Question 11

What are two reasons why blood from normal healthy individuals may contain enzymes?

Answer 11

1. Active secretion (i.e., coagulation precursors such as prothrombin)
2. Release from cells at LOW LEVELS during normal cell turnover.

Question 12

True or False: In healthy individuals blood enzyme levels are fairly constant – equilibrium between release and removal

Answer 12

True

Question 13

Where do most enzymes function?

Answer 13

In cells

Question 14

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

Answer 14

True

Question 15

True or False: Enzymes in blood due to cellular damage function physiologically

Answer 15

False - Enzymes in blood due to cellular damage function no longer function physiologically

Question 16

True or False: Detection of elevated enzyme levels can help to: 1) make/confirm dx; 2) develop prognosis, 3) monitor response to drug therapy

Answer 16

True

Question 17

Two clinical reasons for elevated enzymes in blood?

Answer 17

1) Basal (normal) levels
-normal cellular turnover

2) Pathologies, drugs
-can cause enzyme levels greater than (or sometimes less than) basal levels

Question 18

Answer 18

Question 19

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?

Answer 19

1) ALT
2) LDH
3) Panels/profiles/isoforms

Question 20

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.

Answer 20

True

Question 21

____: 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

Answer 21

Basic Metabolic Panel/Chem 7

Question 22

True or False: A BMP may identify acute problems involving kidney, diabetic shock, respiratory
distress and congestive heart failure

Answer 22

True

Question 23

What 8 chemical blood tests are done for a BMP?

Answer 23

-Serum Sodium
-Serum Potassium
-Serum Chloride
-Serum Calcium
-CO2
-Blood Urea Nitrogen (BUN)
-Creatinine
-Glucose

Question 24

____: A panel of 14 chemical blood tests that adds assessment of liver function to the BMP.

Answer 24

CMP (Chem 12)

Question 25

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

Answer 25

True

Question 26

What 14 chemical blood tests are looked at in a CMP?

Answer 26

Question 27

Renal Profile?

Answer 27

Question 28

Liver Profile?

Answer 28

Question 29

Muscle Profile?

Answer 29

Question 30

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

Answer 30

C. Liver

Question 31

____: urea is a waste product of protein digestion; indicates kidney dysfunction

Answer 31

BUN (blood urea nitrogen)

Question 32

___: waste product of muscle contraction cleared by kidneys; indicates kidney dysfunction.

Answer 32

Creatine

Question 33

What does it mean if BUN/Creatinine ratio is >10:1 to 20:1?

Answer 33

Indicates poor blood flow to kidneys (i.e., congestive heart failure)

Question 34

_____: waste product of purine breakdown cleared by the kidneys; indicates hyperuricemia/gout and kidney disease

Answer 34

Uric Acid

Question 35

___, ___, and ___ assess biliary tract damage - cholestasis

Answer 35

ALK/ALP, GGT, 5’ NT

Question 36

____ assesses chronic decrease vs. acute (normal) liver damage

Answer 36

Albumin

Question 37

___, ____, and ___ assess hepatocellular damage

Answer 37

ALT, AST, and LDH

Question 38

True or False: Bilirubin (T-, D- and I-BIL) assesses heme degradation product diagnostic for liver function, hemolytic anemias

Answer 38

True

Question 39

Where is AST expressed?

Answer 39

AST: skeletal/cardiac muscle, liver

Question 40

____ is a non-specific test for muscle and heart damage

Answer 40

LDH

Question 41

___ is required for muscle cell function; after heart attack, strenuous exercise, muscle injury

Answer 41

Creatine kinase

Question 42

What 4 enzyme tests are used to evaluate pancreatic function (i.e., pancreatitis):

Answer 42

1) amylase 2) lipase 3) lipase:amylase ratio – possible differentiation of alcoholic vs. non-alcoholic acute pancreatitis 4) trypsinogen/Trypsin

Question 43

True or False: Prostate-specific antigen (PSA) – screening test for prostate cancer

Answer 43

True

Question 44

Which elevated serum test result paired with elevated AST levels would be the most specific diagnostic for liver disease?

Question 45

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

Answer 45

A. CK

Question 46

Elevated CK following a heart attack will most likely accompany elevated.. A. Albumin B. BUN C. AST D. Lipase

Answer 46

C. AST

Question 47

____: 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.

Answer 47

Accuracy Precision

Question 48

True or False: Accuracy is the sum of true positive results and true negative results divided by the total number of samples tested.

Answer 48

True

Question 49

What type of distribution defines the reference range?

Answer 49

Gaussian Distribution

Question 50

In a normal population with Gaussian distribution ___% of individuals will be ±1 SD and ___% ±2 SD.

Answer 50

68%; 95%

Question 51

The reference range is the range of values within__ SD of the mean, which covers __ % of healthy individuals

Answer 51

2 ; 95%

Question 52

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.

Answer 52

True

Question 53

What 4 factors influence reference range?

Answer 53

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

Question 54

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?

Answer 54

reaction 1) amino acid composition 2) Cell- and tissue-type in which they function 3) Timing of expression

Question 55

True or False: LDH is a isoenzyme

Answer 55

True

Question 56

_____: catalyzes the reversible formation of lactate from pyruvate (pyruvate from lactate in the liver)

Answer 56

Lactate dehydrogenase (LDH)

Question 57

LDH is a ____(4 subunits) composed of various combinations of __ and __ subunits

Answer 57

tetramer H; M

Question 58

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.

Answer 58

True

Question 59

If LDH-1:LDH-2 >1, what does this indicate? If LDH-5:LDH-4 > 1, what does this indicate?

Answer 59

HEART damage LIVER damage

Question 60

___ Isoenzymes are dimers composed of 2 __ monomers, 2 __ monomers, or one of each

Answer 60

CK Isoenzymes B-monomers; M-monomers

Question 61

CK-BB (CK-1) is found in greatest abundance in the ___ Diagnostic value = ____

Answer 61

Brain CNS damage

Question 62

CK-MB (CK-2) is found in greatest abundance in the ____ Diagnostic value = _____

Answer 62

myocardium Diagnostic value = Acute myocardial infarction (AMI)

Question 63

CK-MM (CK-3) is found in greatest abundance in the ____ muscle Diagnostic value = ____

Answer 63

skeletal muscle Diagnostic value = skeletal muscle damage

Question 64

True or False: LDH and CK Isozymes in Heart Disease

Answer 64

True

Question 65

______heart attacks cause cardiomyocyte damage and release of cardiac enzymes into the blood.

Answer 65

Acute Myocardial Infarctions (AMI)

Question 66

Combination of ____ and ___ isozymes along with ___ and ___ are diagnostic for AMI

Answer 66

CK-MB; LDH-1; Troponins; Myoglobins

Question 67

Cardiac troponin exists as a complex of protein subunits: ___, ____, and ____

Answer 67

TnI, TnT, and TnC

Question 68

True or False: Troponin regulates Ca2+-mediated actin-myosin interactions during cardiac muscle contraction.

Answer 68

True

Question 69

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

Answer 69

E. LDH-5