A patient with chronic extrahepatic biliary obstruction has total bilirubin 14 mg/dL. After surgical relief of the obstruction, serum bilirubin declines far more slowly than expected over several days. Which bilirubin fraction best explains this delayed clearance?

• A Unconjugated bilirubin bound to albumin reversibly
• B Delta bilirubin, conjugated bilirubin covalently linked to albumin ✓
• C Urobilinogen reabsorbed from the gut
• D Biliverdin accumulated in plasma

Explanation

With prolonged cholestasis, conjugated bilirubin undergoes covalent bonding with serum albumin to form delta bilirubin (also called biliprotein). Because it is albumin bound, it cannot be filtered by the glomerulus and it persists in plasma with the long half-life of albumin, so bilirubin levels decline slowly even after the obstruction is relieved. Reversibly bound unconjugated bilirubin dissociates readily and does not behave this way.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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