A patient with a resected terminal ileum 60 cm in length develops fat malabsorption and megaloblastic anemia 2 years later. Which two absorptive functions are specifically lost due to this resection?
- A Iron absorption and folate absorption
- B Bile salt reabsorption and intrinsic factor-bound vitamin B12 absorption ✓
- C Fat-soluble vitamin absorption and calcium absorption
- D Lactose digestion and short-chain fatty acid production
Correct answer: B. Bile salt reabsorption and intrinsic factor-bound vitamin B12 absorption
Explanation
The terminal ileum is the exclusive site for two critical absorptive functions: active reabsorption of conjugated bile salts (via the ASBT transporter, enterohepatic circulation), and receptor-mediated absorption of the intrinsic factor–B12 complex (via cubilin receptors). Resection of sufficient terminal ileum depletes the bile salt pool, causing fat and fat-soluble vitamin malabsorption (steatorrhea), and prevents B12 absorption, producing megaloblastic anemia after 2–3 years when hepatic stores deplete.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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