A patient with carcinoma of the head of the pancreas undergoes successful surgical biliary decompression. Total bilirubin falls initially but plateaus at 6 mg/dL for several weeks despite confirmed patency of the anastomosis. The fraction most responsible for this delayed clearing is:

• A Unconjugated bilirubin bound to albumin in plasma
• B Biliverdin formed by spontaneous oxidation of bilirubin
• C Monoglucuronide bilirubin awaiting renal excretion
• D Conjugated bilirubin covalently linked to albumin (delta bilirubin) ✓

Explanation

In prolonged cholestasis, conjugated bilirubin reacts covalently with albumin to form delta bilirubin (biliprotein). Because it is bound to albumin, which has a plasma half-life of about two to three weeks, it cannot be filtered by glomeruli or excreted in bile and clears only with albumin turnover. This explains the plateau of jaundice after drainage. Unconjugated albumin-bound bilirubin is noncovalent and reversibly dissociates, so it does not account for the delay.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.