Gilbert syndrome is most accurately described by which statement?

• A. Increased hepatic conjugation of bilirubin
• B. Reduced activity of UDP-glucuronosyltransferase
• C. Obstruction of the biliary ducts
• D. Increased bilirubin production

Answer: (B)

Impaired bilirubin conjugation due to reduced UDP-glucuronosyltransferase activity is what Gilbert syndrome is about. The enzyme that normally converts unconjugated bilirubin into a water-soluble, conjugated form in the liver works less efficiently in this condition, so unconjugated bilirubin accumulates, especially during fasting or illness, causing mild jaundice. This contrasts with problems that raise conjugated bilirubin, such as biliary obstruction, or with conditions that increase bilirubin production from hemolysis; those scenarios produce different patterns of hyperbilirubinemia. An increase in hepatic conjugation would actually lower unconjugated bilirubin, not raise it. Thus the statement describing reduced UDP-glucuronosyltransferase activity best explains Gilbert syndrome.