A 19-year-old medical student develops mild jaundice during a period of fasting before exams. Total bilirubin is 3.2 mg/dL with indirect fraction of 2.9 mg/dL. Liver enzymes (ALT, AST, ALP), reticulocyte count, and haptoglobin are all normal. Urine bilirubin is absent. What is the diagnosis?

• A Hemolytic anemia
• B Dubin-Johnson syndrome
• C Gilbert syndrome ✓
• D Crigler-Najjar syndrome type I

Explanation

Gilbert syndrome is a benign hereditary unconjugated hyperbilirubinemia due to reduced UGT1A1 enzyme activity (~30% of normal). Fasting, illness, or stress exacerbates it. Labs show isolated indirect hyperbilirubinemia with normal liver enzymes, no hemolysis (normal reticulocyte count and haptoglobin), and absent urine bilirubin (unconjugated bilirubin is not water-soluble). Hemolysis would show elevated reticulocytes and low haptoglobin. Dubin-Johnson is conjugated hyperbilirubinemia. Crigler-Najjar type I causes severe kernicterus in neonates.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.