Chapter 19: Serum Enzymes
MULTIPLE CHOICE
1. A hydrolase enzyme important during digestion that catalyzes the hydrolysis of starches while
food is still in the mouth is:
a. lipase.
b. lactate dehydrogenase.
c. S-type amylase.
d. P-type amylase.
2. What transferase enzyme is involved in the conversion of the stored form of energy to usable
energy (adenosine triphosphate [ATP]) within cardiac myocytes?
a. Creatine kinase
b. Aspartate aminotransferase
c. Lactate dehydrogenase
d. Troponinase
3. Increased enzyme activity is typically observed in serum or plasma:
a. only if a genetic abnormality is present.
b. only following mitochondrial damage.
c. following injury or damage to tissue.
d. only if hepatic damage has occurred.
4. At present, the major diagnostic usefulness of tartrate-resistant acid phosphatase type 5b is in
its use as a marker of conditions with:
a. a liver involvement.
b. pancreatitis.
c. involvement of the prostate gland.
d. an osteolytic component.
5. Which one of the following statements concerning lipase is incorrect?
a. Lipase is localized partly in cells of the pancreas.
b. Following an acute attack of pancreatitis, lipase activity increases within 4 to 8
hours.
c. Lipase is a small enzyme that can be detected in urine.
d. Lipase is considered to be in the hydrolase class of enzymes.
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6. The principal source of serum cholinesterase (CHE) in blood is:
a. liver.
b. skeletal muscle.
c. pancreas.
d. bone.
7. Which one of the following enzymes catalyzes the transfer of an amino group to alpha-
ketoglutarate with the formation of oxaloacetate and glutamate?
a. Alanine aminotransferase (ALT)
b. Aspartate aminotransferase (AST)
c. Alkaline phosphatase (ALP)
d. 5'-Nucleotidase (NTP)
ANS: B
See Figure 19-4; AST catalyzes the reaction of aspartate and oxoglutarate to oxaloacetate and
8. If you were asked by your laboratory director to set up an enzyme profile (group of tests)
specifically to assess hepatobiliary (biliary obstruction) disease, which one of the following
sets of enzymes would be most appropriate?
a. NTP, ALP, and -glutamyltransferase (GGT)
b. ALP, GGT, and CK
c. CHE, NTP, and CK
d. LD, CK, ALT, and AST
9. A physician orders several laboratory tests on a 55-year-old male patient who is complaining
of generalized (all-over) pain, stiffness, fatigue, and headaches. Based on the following serum
test results, what is the most likely diagnosis: ALP—significantly increased, GGT— normal?
a. Biliary obstruction
b. Cirrhosis
c. Primary metastatic liver cancer
d. Bone disease
10. Which is the most sensitive enzyme for monitoring chronic alcoholic liver disease?
a. ALP
b. GGT
c. NTP
d. AST
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11. Activators that are required for normal CK activity include:
a. pyroxidal phosphate and magnesium.
b. magnesium, manganese, and cobalt.
c. magnesium only.
d. NAD and NADH.
12. Which of the following products are formed from the forward reaction catalyzed by ALT?
a. Pyruvate and glutamate
b. Aspartate and alanine
c. Oxaloacetate and glutamate
d. Alanine and alpha ketoglutarate
13. All of the statements below about the clinically significant phosphatases are true except they:
a. catalyze the transfer of amine groups to ketoacids.
b. are divided into two classes based upon pH required for their respective reactions.
c. are isoenzyme forms of the phosphatases.
d. are classified as hydrolases.
14. A 10-year-old girl visits her pediatrician with the complaint of bone pain. Following enzyme
studies, these results were obtained: ALP 3.5 higher than upper reference limit; NTP normal.
These results are consistent with a diagnosis of:
a. hepatobiliary disease.
b. normal bone growth.
c. viral hepatitis.
d. bone cancer.
15. A 37-year-old woman who thinks she might be pregnant visits her physician with a complaint
of upper right quadrant pain. Blood samples are obtained. Increased enzyme activity was seen
for ALP, AST, lactate dehydrogenase (LD), and GGT. The ALP was 10 times higher than the
upper reference limit. A hepatitis panel and a pregnancy test had negative results. Gel
electrophoresis was done to separate ALP isoenzymes, with a dense liver band and what
appeared to be a diffuse placental band. If this woman’s physician has ruled out pregnancy,
activity of what other serum enzyme could be measured to differentiate between hepatobiliary
disease and liver disease?
a. NTP
b. ALT
c. Aldolase
d. CHE
16. A 37-year-old woman who thinks she might be pregnant visits her physician with a complaint
of upper right quadrant pain. Blood samples are obtained. Increased enzyme activity was seen
for ALP, AST, LD, and GGT. The ALP was 10 times higher than the upper reference limit. A
hepatitis panel and a pregnancy test had negative results. Gel electrophoresis was done to
separate ALP isoenzymes, with a dense liver band and what appeared to be a diffuse placental
band. If there is not a pregnancy, what is the name given to the observed isoenzyme band that
migrates in the same region as the placental isoenzyme?
a. Stable placental isoenzyme
b. Regan isoenzyme
c. S-AMY isoenzyme
d. LD-X isoenzyme
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17. Tartrate-resistant acid phosphatase (TR-ACP) that is present in unhemolyzed serum is
synthesized mainly in:
a. erythrocytes.
b. cells of the prostate gland.
c. osteoclasts.
d. hepatocytes.
18. Heart tissue contains which of the following CK isoenzymes?
a. MM only
b. MB only
c. BB only
d. MM and MB
19. Why is heparin the only acceptable anticoagulant to use when obtaining blood samples for
ALP analysis?
a. Heparin contains necessary cofactors for ALP to reach full enzyme activity.
b. Other anticoagulants contain inhibitors of magnesium, which is a required cofactor
for ALP activation.
c. Heparin maintains the integrity of the ALP molecule through freeze-thaw cycles.
d. Other anticoagulants bind ALP and reduce its ability to react with substrate in
enzyme reactions.
20. A specimen is received in a green top tube (heparin) with a request for alkaline phosphatase
analysis. The plasma is separated and the test is performed. How will this specimen type
affect the ALP results?
a. There will be no effect, because this is an acceptable specimen for this test.
b. Results will be falsely decreased.
c. Results will be falsely increased.
21. Which one of the following statements concerning lipase (LPS) is incorrect?
a. When comparing LPS with amylase in diagnosis of acute pancreatitis, amylase is a
more specific diagnostic finding.
b. Following an acute attack of pancreatitis, lipase levels elevate within 4 to 8 hours.
c. Lipase is a hydrolase that breaks down glycerol esters of long chain free fatty
acids.
d. Most serum lipase activity is derived from pancreas, but gastrointestinal mucosa
contributes a small amount.
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22. Which of the following statements is incorrect concerning creatine kinase (CK)?
a. CK catalyzes the conversion of creatine and ADP to creatine phosphate and ATP.
b. Total CK activity can be elevated in skeletal muscle disease.
c. The subunits of CK can combine to form three different CK isoenzymes.
d. CK is classified as a transferase enzyme.
23. The recommended assay, because of its specificity and sensitivity for the measurement of the
activity of the CK-MB isoenzyme, is the:
a. immunoinhibition assay.
b. polyclonal competitive binding immunoassay.
c. monoclonal sandwich immunoassay.
d. isoenzyme electrophoresis.
24. The usefulness of analyzing lipoprotein-associated phospholipase A2 for the identification of
individuals at risk for future cardiovascular events is because of its:
a. release of granules that destabilize complex plaque.
b. ability to transform stable coronary artery plaques to unstable ones.
c. release during inflammatory events such as coronary artery blockage.
d. upregulation in atherosclerotic lesions, particularly complex plaque.
25. Because your immunoassay analyzer is down for maintenance, you have performed an
immunoinhibition assay to determine the relative presence of CK isoenzymes in an individual
who has presented with acute upper body pain. The assay reveals a strong activity after
inhibition of CK-M subunits using a monoclonal antibody. This result indicates:
a. definitive evidence for an acute cardiac event having occurred.
b. that the individual takes part in strenuous exercise.
c. a nonspecific result due to possible presence of CK-B subunits.
d. definitive evidence for possible gastrointestinal problems.
26. Certain muscle relaxants are hydrolyzed by CHE during surgical procedures. If an individual
with the atypical (Ea) gene variant is exposed to this relaxant, what would occur?
a. Decreased drug metabolism at the neuromuscular junction with resulting muscle
weakness
b. Increased drug metabolism over time with a shortened period of relaxant effect and
the patient awakening during surgery
c. Decreased drug metabolism over time with resultant paralysis of respiratory
muscles
d. Formation of autoantibodies against choline receptors, with resulting general
weakness
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27. A severely hemolyzed serum specimen from an individual with hemolytic anemia is received
in the laboratory with a request for total CK and LD enzymes. How will the results of these
analyses be falsely affected by the condition of the specimen?
a. LD decreased, CK increased
b. LD increased, CK increased
c. LD decreased, CK decreased
d. LD increased, CK decreased
28. A phosphotransferase enzyme that has increased activity when injury, inflammation, or
necrosis of skeletal muscle occurs is:
a. ALP.
b. ACP.
c. CK.
d. LD.
MATCHING
Match the enzyme with its correct enzyme classification.
a. Creatine kinase
b. Lactate dehydrogenase
c. Alkaline phosphatase
1. Oxidoreductase
2. Transferase
3. Hydrolase
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1.
phosphates from one molecule to another. LD is an oxidoreductase because it moves hydrogen
molecules. ALP and amylase are both hydrolases because they catalyze hydrolysis reactions.
DIF: 1
REF: Page 331
OBJ: 1 | 3
MSC: CK, along with GGT, ALT, and AST, are transferases in that they transfer amino acids or
phosphates from one molecule to another. LD is an oxidoreductase because it moves hydrogen
molecules. ALP and amylase are both hydrolases because they catalyze hydrolysis reactions.
3. ANS: C
DIF: 1
REF: Page 325
OBJ: 1 | 3
MSC: CK, along with GGT, ALT, and AST, are transferases in that they transfer amino acids or
phosphates from one molecule to another. LD is an oxidoreductase because it moves hydrogen
molecules. ALP and amylase are both hydrolases because they catalyze hydrolysis reactions.
Match the enzyme with its correct substance required for enzyme reaction. Answers may be
used more than once, once, or not at all.
a. Creatine kinase
b. Aspartate aminotransferase
c. Amylase
4. Pyridoxal phosphate
5. Magnesium
6. Calcium
4.
DIF:
2
REF:
Page 320
OBJ: 3
MSC: CK requires magnesium, which is an obligatory activating ion that forms complexes with ATP
and ADP; ALP requires magnesium as its activator also. AST requires pyridoxal-5'-phosphate (P-5'-P)
and its amino analogue, pyridoxamine-5'-phosphate, as coenzymes in the amino-transfer reaction.
Calcium is absolutely required for functional integrity of amylase.
5.
DIF:
2
REF:
Page 322
OBJ: 3
MSC: CK requires magnesium, which is an obligatory activating ion that forms complexes with ATP
and ADP; ALP requires magnesium as its activator also. AST requires pyridoxal-5'-phosphate (P-5'-P)
and its amino analogue, pyridoxamine-5'-phosphate, as coenzymes in the amino-transfer reaction.
Calcium is absolutely required for functional integrity of amylase.
6.
DIF:
2
REF:
Page 328
OBJ: 3
MSC: CK requires magnesium, which is an obligatory activating ion that forms complexes with ATP
and ADP; ALP requires magnesium as its activator also. AST requires pyridoxal-5'-phosphate (P-5'-P)
and its amino analogue, pyridoxamine-5'-phosphate, as coenzymes in the amino-transfer reaction.
Calcium is absolutely required for functional integrity of amylase. Answers available here
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