Clinical Enzymology and Organ Function Tests MCQs

Biochemistry · 40 free questions with answers & explanations.

1. A 58-year-old man presents 6 hours after acute chest pain. Troponin I is elevated. Which isoenzyme pattern of CK would be most diagnostically specific for myocardial injury at this time point?
2. In a patient with cholestatic jaundice, which enzyme ratio would most reliably distinguish intra-hepatic cholestasis from extrahepatic biliary obstruction when imaging is equivocal?
3. A patient with chronic alcoholism shows elevated AST:ALT ratio of 2.5:1 with elevated GGT. The most probable enzymatic mechanism explaining the disproportionate AST elevation is:
4. Serum amylase is elevated 5-fold above normal in a patient with abdominal pain. Which additional finding would most specifically confirm acute pancreatitis rather than other causes of hyperamylasemia?
5. The De Ritis ratio (AST/ALT) is used clinically. A ratio >2 in acute hepatocellular injury most strongly suggests which underlying etiology?
6. A 58-year-old man presents 18 hours after onset of crushing chest pain. Serum troponin I is elevated, but CK-MB has already returned to normal. Which property of troponin I makes it superior to CK-MB for detecting myocardial infarction in this time window?
7. In obstructive jaundice, which of the following enzyme patterns is MOST characteristic and helps distinguish it from hepatocellular jaundice?
8. A 45-year-old alcoholic woman has AST 280 U/L and ALT 130 U/L. The De Ritis ratio (AST:ALT) is approximately 2.2. Which explanation best accounts for this pattern in alcoholic liver disease?
9. Amylase isoenzyme electrophoresis of a serum sample shows a predominant S-type (salivary) isoenzyme with only mildly elevated P-type (pancreatic). This finding would be MOST consistent with which condition?
10. Creatinine clearance (CrCl) consistently underestimates true GFR in which clinical scenario, making cystatin C a superior GFR marker?
11. Lactate dehydrogenase (LDH) has five isoenzymes (LDH1–LDH5). In acute myocardial infarction with a 'flipped LDH' pattern, which isoenzyme ratio becomes abnormal?
12. A 55-year-old man presents 18 hours after onset of crushing chest pain. Serum troponin-I is markedly elevated. Which property of cardiac troponin-I makes it MOST superior to CK-MB as a biomarker for myocardial injury?
13. A liver biopsy shows significant hepatocellular necrosis. Among the serum enzyme markers, which pattern BEST distinguishes hepatocellular injury from pure cholestasis?
14. A 40-year-old alcoholic has a serum AST:ALT ratio of 3:1 with elevated GGT. The MOST likely biochemical reason for the disproportionate AST elevation in alcoholic liver disease is:
15. Serum lipase is preferred over serum amylase for the diagnosis of acute pancreatitis because:
16. A patient with suspected prostate cancer has a total PSA of 9 ng/mL. The free PSA:total PSA ratio is 0.08 (8%). Which interpretation is CORRECT?
17. In renal function testing, cystatin C is considered superior to serum creatinine as an early marker of GFR decline because:
18. A 58-year-old man is admitted with acute chest pain. Serial troponin-I levels are measured at 0, 6, and 12 hours. The attending physician notes that high-sensitivity troponin-I (hs-TnI) is preferred over conventional troponin because it allows earlier rule-out. Which property of hs-TnI assay primarily enables a 0/3-hour rule-out algorithm?
19. In a patient with suspected acute pancreatitis, serum lipase is measured rather than amylase. The primary reason lipase is preferred in this clinical setting is:
20. Plasma cholinesterase (pseudocholinesterase) activity is markedly reduced in a patient prior to surgery. This finding is most clinically significant because it predicts prolonged action of which drug?
21. A 45-year-old woman with alcoholic liver disease has AST:ALT ratio of 2.8:1. This ratio is elevated because:
22. Gamma-glutamyl transferase (GGT) is elevated in a patient with no clinical features of liver disease but who is on enzyme-inducing antiepileptics. This elevation is best explained by:
23. Cystatin C is increasingly used as a marker of glomerular filtration rate (GFR) in preference to creatinine in certain clinical contexts. In which specific population is cystatin C most superior to creatinine-based GFR estimation?
24. A 52-year-old male presents 8 hours after onset of severe chest pain. His serum troponin I is markedly elevated. Which property of cardiac troponin I makes it MOST specific for myocardial injury compared to troponin T?
25. In a patient with obstructive jaundice due to carcinoma head of pancreas, which enzyme pattern is MOST characteristic?
26. A 45-year-old alcoholic presents with serum AST 280 U/L, ALT 110 U/L, and markedly elevated GGT. The AST:ALT ratio of >2 in alcoholic liver disease is PRIMARILY due to:
27. A 3-year-old child has recurrent hypoglycemia, elevated serum ALT, and hyperammonemia after fasting. Liver biopsy shows microvesicular steatosis. Serum CK is normal. The enzyme defect MOST likely involves:
28. Amylase and lipase are both elevated in acute pancreatitis. In which clinical situation does serum lipase have a decisive advantage over amylase for diagnosis?
29. A patient with chronic renal failure has serum creatinine 8 mg/dL, BUN 80 mg/dL, and a BUN:creatinine ratio of 10:1. This ratio is MORE LIKELY caused by:
30. A 55-year-old man is admitted with chest pain. Serial troponin I measurements at 0, 3, and 6 hours are 0.02, 4.8, and 9.2 ng/mL respectively. Which property of cardiac troponin I makes it superior to CK-MB for late presentation (48–72 hours after onset)?
31. Gamma-glutamyl transferase (GGT) is elevated in isolation in a 40-year-old asymptomatic male with no jaundice. Which of the following best explains this finding?
32. A 30-year-old female presents with acute pancreatitis. Serum amylase is 900 U/L on day 1. By day 5, amylase normalises but serum lipase remains 600 U/L. What explains this difference in kinetics?
33. On LFT interpretation, which combination indicates the most specific pattern for intrahepatic cholestasis as opposed to hepatocellular disease?
34. A researcher uses the Jaffe reaction to measure serum creatinine and notes that cephalosporins in the sample spuriously elevate the result. Which method best eliminates this interference for accurate RFT in patients on beta-lactam antibiotics?
35. A 58-year-old man presents 18 hours after chest pain. Troponin I is elevated. Which isoenzyme pattern of CK would confirm myocardial injury if troponin were unavailable?
36. Gamma-glutamyl transferase (GGT) is markedly elevated in isolation in a 45-year-old asymptomatic man. ALT, AST, and ALP are normal. The most likely explanation is:
37. In acute pancreatitis, serum lipase is preferred over amylase for diagnosis because:
38. A patient with obstructive jaundice has ALP 900 U/L, GGT 800 U/L, ALT 90 U/L. The ALP:ALT ratio is 10. This pattern is most consistent with:
39. Lactate dehydrogenase (LDH) isoenzyme pattern LDH1 > LDH2 (flipped pattern) is characteristic of:
40. 5'-Nucleotidase elevation alongside ALP is used clinically to confirm: