A 55-year-old patient undergoes ileal resection (>100 cm) for Crohn's disease. Which bile acid-related complication and its specific pathophysiology is MOST expected?
- A Fat-soluble vitamin malabsorption due to reduced bile acid pool causing type A (secretory) diarrhoea
- B Bile acid malabsorption causing type B (cholerheic) diarrhoea AND fat malabsorption due to insufficient micellar solubilisation ✓
- C Cholestatic jaundice due to backpressure of bile into the liver
- D Calcium oxalate nephrolithiasis only, without steatorrhoea
Explanation
The terminal ileum is the exclusive site of bile acid reabsorption (enterohepatic circulation). After >100 cm ileal resection, the bile acid pool is irreversibly depleted, causing two problems: (1) cholerheic (bile acid) diarrhoea as unabsorbed bile acids spill into the colon (type B), AND (2) fat malabsorption/steatorrhoea because insufficient bile acids remain for micellar solubilisation of fat. Small ileal resections (<100 cm) cause only type B diarrhoea (hepatic compensation maintains pool). Calcium oxalate kidney stones also occur due to increased colonic oxalate absorption.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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