A 60-year-old man who underwent Billroth II gastrectomy 15 years ago now reports postprandial bloating, foul-smelling loose stools, and macrocytic anaemia. Which investigation provides the best non-invasive confirmation of the underlying mechanism?
- A Faecal fat quantification over 72 hours
- B Schilling test with intrinsic factor correction
- C Hydrogen breath test showing an early peak after glucose ingestion ✓
- D Serum anti-parietal cell and anti-intrinsic factor antibodies
Explanation
Stagnant fluid in the afferent blind loop permits bacterial overgrowth, producing deconjugated bile acids that impair micelle formation and bacteria that consume luminal vitamin C12. The glucose hydrogen breath test shows an early hydrogen peak as bacteria ferment sugar in the proximal small intestine, confirming small intestinal bacterial overgrowth non-invasively. Faecal fat only documents steatorrhoea generically, antibodies diagnose autoimmune gastritis, and the Schilling test is largely obsolete and cannot separate overgrowth from ileal disease reliably.
Reference: Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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