Which abnormality is the fundamental defect responsible for the formation of cholesterol gallstones?

• A Excessive secretion of unconjugated bilirubin into bile
• B Increased bacterial deconjugation of bile salts within the gallbladder
• C Deficiency of pancreatic lipase causing fat malabsorption
• D Supersaturation of bile with cholesterol relative to bile acids and lecithin ✓

Explanation

Cholesterol is insoluble in water and is held in micelles by bile acids and lecithin. When cholesterol secretion exceeds the solubilizing capacity of these components, bile becomes lithogenic and crystals nucleate, often accelerated by gallbladder hypomotility and mucus. Excess unconjugated bilirubin drives pigment stones, not cholesterol stones, and bacterial deconjugation is the mechanism behind brown pigment stones.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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