A 30-year-old asymptomatic man is found to have serum bilirubin of 3.2 mg/dL (indirect 2.8, direct 0.4) on a routine preoperative check. All other LFTs including ALT, AST, and ALP are normal. CBC, reticulocyte count, and peripheral smear are normal. The bilirubin rises significantly with fasting and returns to normal with caloric intake. The diagnosis is:
- A Gilbert syndrome ✓
- B Dubin-Johnson syndrome
- C Rotor syndrome
- D Crigler-Najjar type II
Explanation
Gilbert syndrome is caused by a UGT1A1 promoter polymorphism (TA repeat expansion) reducing UDP-glucuronosyltransferase activity by 30–70%, causing benign unconjugated hyperbilirubinemia. Characteristically, bilirubin rises with fasting, stress, or illness and normalizes with caloric intake — a diagnostic feature. All other liver function tests are normal and there is no hemolysis. Dubin-Johnson syndrome shows elevated conjugated bilirubin; Rotor syndrome also shows conjugated hyperbilirubinemia. Crigler-Najjar type II has higher bilirubin levels (>6 mg/dL) and more persistent elevation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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