Hydrogen breath testing - substrate and mechanism (SIBO diagnosis)
Core concept
- Hydrogen breath testing detects bacterial fermentation of an ingested substrate -> H2 (+/- methane) absorbed into blood -> exhaled and measured
- Human cells cannot produce H2 - any breath H2 rise reflects bacterial metabolism, either normal colonic flora or, if early, small bowel bacterial overgrowth
- Substrate choice defines what is tested: glucose or lactulose for SIBO; lactose for lactase deficiency; fructose for fructose malabsorption
3 more sections, plus exam facts
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