Diagnostic applications of enzymes MCQs With Answer

Diagnostic applications of enzymes MCQs With Answer are essential for B. Pharm students preparing for clinical pharmacology and therapeutic monitoring. Understanding enzyme assays, isoenzymes, reference ranges, and pre-analytical variables helps pharmacists interpret lab reports for liver, cardiac, pancreatic and bone disorders. This set emphasizes practical concepts: enzyme kinetics, assay methods (colorimetric, kinetic, ELISA), diagnostic specificity and sensitivity, and drug-induced enzyme changes. Keywords included: diagnostic enzymes, enzyme assays, clinical diagnostics, liver enzymes, cardiac enzymes, pancreatic enzymes, and enzyme kinetics. The questions reinforce interpretation skills and real-world lab considerations to bridge theory with pharmacy practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary reason enzymes are useful as diagnostic biomarkers?

• They are secreted in constant amounts regardless of tissue damage
• They are tissue-specific and released into blood after cell damage
• They always remain inactive in circulation
• They bind irreversibly to antibodies

Correct Answer: They are tissue-specific and released into blood after cell damage

Q2. Which enzyme is most specific for hepatocellular injury?

• Alkaline phosphatase (ALP)
• Aspartate aminotransferase (AST)
• Alanine aminotransferase (ALT)
• Gamma-glutamyl transferase (GGT)

Correct Answer: Alanine aminotransferase (ALT)

Q3. An AST/ALT ratio greater than 2 is classically associated with which condition?

• Viral hepatitis
• Alcoholic liver disease
• Primary biliary cholangitis
• Acute pancreatitis

Correct Answer: Alcoholic liver disease

Q4. Which cardiac enzyme isoform is traditionally used to diagnose acute myocardial infarction but has largely been replaced by troponins?

• Lactate dehydrogenase (LDH-1)
• Creatine kinase MB isoform (CK-MB)
• Alanine aminotransferase (ALT)
• Amylase

Correct Answer: Creatine kinase MB isoform (CK-MB)

Q5. Which enzyme shows an early and sustained rise after myocardial injury and is considered the most specific cardiac biomarker?

• CK-MB
• Troponin I/T
• AST
• ALP

Correct Answer: Troponin I/T

Q6. Which enzyme is most useful in diagnosing acute pancreatitis due to higher specificity?

• Serum amylase
• Serum lipase
• Alkaline phosphatase
• Lactate dehydrogenase

Correct Answer: Serum lipase

Q7. Lactate dehydrogenase (LDH) isoenzyme pattern with higher LDH-1 than LDH-2 (flipped pattern) suggests what?

• Hemolysis only
• Myocardial infarction
• Hepatic cholestasis
• Bone disease

Correct Answer: Myocardial infarction

Q8. Alkaline phosphatase (ALP) elevation with increased gamma-glutamyl transferase (GGT) most likely indicates which pathology?

• Bone disease
• Hepatobiliary obstruction
• Acute pancreatitis
• Muscle injury

Correct Answer: Hepatobiliary obstruction

Q9. Which pre-analytical factor artificially elevates serum potassium, AST and LDH levels?

• Delayed centrifugation
• Hemolysis of the sample
• Use of EDTA tube instead of serum
• Excessive refrigeration

Correct Answer: Hemolysis of the sample

Q10. The SI unit katal measures enzyme activity as:

• Micromoles per liter per minute
• One mole of substrate converted per second
• Units per milliliter
• International units per liter

Correct Answer: One mole of substrate converted per second

Q11. Michaelis constant (Km) indicates what property of an enzyme for a substrate?

• Maximum velocity of the enzyme
• Substrate concentration at half Vmax, reflecting affinity
• Turnover number of enzyme molecules
• Enzyme inhibition constant

Correct Answer: Substrate concentration at half Vmax, reflecting affinity

Q12. Which enzyme assay principle uses an antibody to detect an antigen and an enzyme to produce a measurable signal?

• Electrophoresis
• Mass spectrometry
• Enzyme-linked immunosorbent assay (ELISA)
• Colorimetric catalytic assay

Correct Answer: Enzyme-linked immunosorbent assay (ELISA)

Q13. Which organ is the primary source of gamma-glutamyl transferase (GGT) used in diagnostics?

• Heart
• Liver and biliary tract
• Bone
• Pancreas

Correct Answer: Liver and biliary tract

Q14. What is the clinical significance of an isolated rise in ALP with normal ALT/AST?

• Pure hepatocellular injury
• Cholestasis or bone disease—further differentiation needed
• Acute myocardial infarction
• Laboratory error only

Correct Answer: Cholestasis or bone disease—further differentiation needed

Q15. Which enzyme is a sensitive marker for skeletal muscle damage and is increased with statin-induced myopathy?

• Alanine aminotransferase (ALT)
• Creatine kinase (CK)
• Alkaline phosphatase (ALP)
• Lactate dehydrogenase (LDH)

Correct Answer: Creatine kinase (CK)

Q16. Which statement about isoenzymes is correct?

• Isoenzymes have different catalytic mechanisms
• Isoenzymes are identical proteins from the same gene
• Isoenzymes are different molecular forms of an enzyme from different tissues
• Isoenzymes are always found only inside cells

Correct Answer: Isoenzymes are different molecular forms of an enzyme from different tissues

Q17. Which enzyme is elevated in obstructive jaundice and is useful to distinguish liver from bone ALP?

• Creatine kinase (CK)
• Gamma-glutamyl transferase (GGT)
• Amylase
• Lipase

Correct Answer: Gamma-glutamyl transferase (GGT)

Q18. In enzyme assays, what does a kinetic (rate) assay measure?

• Total protein concentration only
• Change in absorbance over time to calculate activity
• Presence or absence of enzyme qualitatively
• Molecular weight of the enzyme

Correct Answer: Change in absorbance over time to calculate activity

Q19. Which enzyme is most indicative of bone formation when measuring bone-specific isoforms?

• Bone-specific alkaline phosphatase
• Serum amylase
• GGT
• AST

Correct Answer: Bone-specific alkaline phosphatase

Q20. Which of the following drugs is known to cause transaminase elevation that requires monitoring?

• Acetaminophen in overdose
• Ibuprofen at therapeutic doses
• Topical hydrocortisone
• Oral contraceptives never cause enzyme changes

Correct Answer: Acetaminophen in overdose

Q21. How does hemolysis affect AST measurements compared to ALT?

• Hemolysis decreases AST only
• Hemolysis increases AST more markedly than ALT
• Hemolysis does not affect either enzyme
• Hemolysis increases ALT more than AST

Correct Answer: Hemolysis increases AST more markedly than ALT

Q22. Which enzyme assay method measures an enzyme’s catalytic activity rather than its concentration?

• Immunoassay
• Enzymatic catalytic assay (functional assay)
• Western blot for enzyme protein
• DNA PCR of enzyme gene

Correct Answer: Enzymatic catalytic assay (functional assay)

Q23. Which pancreatic enzyme remains elevated longer and is preferred for late-presenting acute pancreatitis cases?

• Amylase
• Lipase
• GGT
• ALP

Correct Answer: Lipase

Q24. Which laboratory artifact can falsely lower measured enzyme activities?

• Delayed refrigeration of the sample
• Repeated freeze-thaw cycles
• Using serum instead of plasma
• Prompt centrifugation

Correct Answer: Repeated freeze-thaw cycles

Q25. Which enzyme is elevated in obstructive biliary disease and is heat-stable compared to other ALP isoforms?

• Bone ALP
• Placental ALP
• Hepatic ALP isoform
• Intestinal ALP

Correct Answer: Hepatic ALP isoform

Q26. Enzyme induction by a drug results in which of the following?

• Decreased enzyme synthesis
• Increased enzyme synthesis leading to higher measured activity
• Immediate irreversible enzyme inhibition
• No change in enzyme levels

Correct Answer: Increased enzyme synthesis leading to higher measured activity

Q27. Which test distinguishes between pancreatic and salivary sources of amylase?

• Amylase isoenzyme analysis
• Serum creatinine
• ALT/AST ratio
• GGT measurement

Correct Answer: Amylase isoenzyme analysis

Q28. Which enzyme is commonly used as a tumor marker for germ cell tumors historically?

• Alkaline phosphatase
• Placental alkaline phosphatase
• Amylase
• Creatine kinase

Correct Answer: Placental alkaline phosphatase

Q29. Which enzyme measurement would most likely be ordered to evaluate suspected cholestasis?

• Serum lipase only
• Alkaline phosphatase and GGT
• CK-MB only
• Amylase and lipase

Correct Answer: Alkaline phosphatase and GGT

Q30. Which enzyme is least likely to be elevated in muscle injury?

• Creatine kinase
• AST
• ALT
• Amylase

Correct Answer: Amylase

Q31. What does a rising pattern of CK-MB over serial measurements generally indicate?

• Laboratory contamination
• Ongoing myocardial necrosis
• Normal biological variability
• Renal failure only

Correct Answer: Ongoing myocardial necrosis

Q32. Which analytic technique separates enzyme isoforms based on electric charge and size?

• Chromatography
• Isoenzyme electrophoresis
• Mass spectrometry without separation
• Immunoturbidimetry

Correct Answer: Isoenzyme electrophoresis

Q33. A patient on long-term enzyme-inducing anticonvulsants may show which laboratory change?

• Decreased hepatic enzyme activities
• Elevated hepatic enzyme activities due to induction
• Complete absence of enzymes in blood
• Unchanged enzyme levels always

Correct Answer: Elevated hepatic enzyme activities due to induction

Q34. Which factor most affects the precision of an enzyme assay?

• Time of day the sample is drawn only
• Standardization of temperature and reaction time
• Patient age alone
• Brand of syringe used

Correct Answer: Standardization of temperature and reaction time

Q35. In forensic toxicology, elevated serum acetylcholinesterase indicates exposure to which class of agents?

• Organophosphate pesticides leading to decreased AChE
• Carbamates leading to increased AChE
• Agents that usually inhibit acetylcholinesterase causing decreased activity
• No change expected with toxic exposure

Correct Answer: Agents that usually inhibit acetylcholinesterase causing decreased activity

Q36. Which statement about enzyme half-life in circulation is true for marker interpretation?

• Short half-life limits detection window after injury
• Long half-life makes the marker disappear quickly
• Half-life is irrelevant in diagnostics
• All enzymes have identical half-lives

Correct Answer: Short half-life limits detection window after injury

Q37. Which of the following is a common colorimetric substrate used in peroxidase-based enzyme assays?

• p-Nitrophenyl phosphate
• 3,3′,5,5′-Tetramethylbenzidine (TMB)
• NADH
• Glucose

Correct Answer: 3,3′,5,5′-Tetramethylbenzidine (TMB)

Q38. For therapeutic drug monitoring, elevated hepatic enzymes may indicate what action is needed?

• Increase the dose regardless of symptoms
• Assess for drug-induced hepatotoxicity and consider dose modification or cessation
• Ignore unless patient has fever
• Switch to a drug that is more hepatotoxic

Correct Answer: Assess for drug-induced hepatotoxicity and consider dose modification or cessation

Q39. Which enzyme is used as a diagnostic marker for skeletal metastasis because of bone turnover?

• AST
• Bone-specific alkaline phosphatase
• Pancreatic lipase
• CK-MB

Correct Answer: Bone-specific alkaline phosphatase

Q40. Which condition most commonly causes marked elevation of serum amylase but relatively modest lipase rise?

• Acute pancreatitis from gallstones
• Macroamylasemia
• Pancreatic carcinoma with duct obstruction
• Normal healthy state

Correct Answer: Macroamylasemia

Q41. When interpreting enzyme results, which concept refers to the balance between sensitivity and specificity of a test?

• Analytical range
• Diagnostic accuracy and predictive values
• Isoenzyme composition
• Pre-analytical variability

Correct Answer: Diagnostic accuracy and predictive values

Q42. Which enzyme is released from the liver and muscle and catalyzes conversion of lactate to pyruvate?

• Lactate dehydrogenase (LDH)
• Amylase
• Alkaline phosphatase
• GGT

Correct Answer: Lactate dehydrogenase (LDH)

Q43. In chronic cholestatic liver disease, which enzyme pattern is typically seen?

• Predominant rise in transaminases (ALT/AST)
• Predominant rise in cholestatic enzymes ALP and GGT
• Only CK elevation
• Only amylase rise

Correct Answer: Predominant rise in cholestatic enzymes ALP and GGT

Q44. Which analytical interference can result from lipemic samples in enzyme assays?

• Increased optical clarity improving accuracy
• Light scattering leading to falsely elevated absorbance readings
• No effect on spectrophotometric assays
• Complete destruction of enzymes

Correct Answer: Light scattering leading to falsely elevated absorbance readings

Q45. Which enzyme assay is most appropriate for assessing cholestasis in pregnancy where ALP is naturally elevated?

• Use ALP alone without other tests
• Measure GGT to confirm hepatic source of ALP
• Measure CK instead of ALP
• Ignore enzyme testing in pregnancy

Correct Answer: Measure GGT to confirm hepatic source of ALP

Q46. Which laboratory technique provides high specificity for enzyme identification by measuring mass-to-charge ratio?

• Isoenzyme electrophoresis
• Mass spectrometry
• ELISA only
• Simple colorimetric test

Correct Answer: Mass spectrometry

Q47. Which statement best describes the role of point-of-care (POC) enzyme testing?

• POC tests are always more accurate than central lab tests
• POC tests provide rapid results but may sacrifice some analytical precision
• POC testing requires no quality control
• POC tests replace the need for confirmatory central lab testing in all cases

Correct Answer: POC tests provide rapid results but may sacrifice some analytical precision

Q48. Which enzyme measurement is commonly monitored to detect early re-infarction after myocardial infarction?

• Alkaline phosphatase
• Serial CK-MB measurements
• Serum amylase only
• Bone-specific ALP

Correct Answer: Serial CK-MB measurements

Q49. A marked isolated elevation of alkaline phosphatase in a child is most suggestive of what?

• Normal variant due to bone growth
• Acute pancreatitis
• Acute myocardial infarction
• Renal failure

Correct Answer: Normal variant due to bone growth

Q50. When interpreting enzyme test results, which multidisciplinary approach improves diagnostic accuracy?

• Relying solely on a single enzyme level
• Combining clinical assessment, serial enzyme measurements and complementary tests
• Ignoring patient history
• Using only imaging without laboratory data

Correct Answer: Combining clinical assessment, serial enzyme measurements and complementary tests

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com