Assessing the Prevalence and Epidemiological Characteristics of Small Intestinal Bacterial Overgrowth (SIBO) in Patients With Autoimmune Gastritis(AIG) Through Hydrogen and Methane Breath Testing(HMBT).

The hydrogen and methane breath testingt(HMBT) is a non-invasive method based on gas analysis of gut microbiota metabolomics.Normal human metabolic processes do not produce methane and hydrogen, and all methane and hydrogen in exhaled breath come from metabolites produced during the fermentation of substrates by gut microbiota. About 14-21% of the gas can diffuse through the intestinal mucosa to the bloodstream, circulate through the bloodstream to the alveoli, and be exhaled through gas exchange.Based on substrate properties, separate and measure methane and hydrogen concentrations from exhaled breath for non-invasive, convenient, and accurate diagnosis of microbial imbalance/small intestine bacterial overgrowth (SIBO)