Hydrogen breath testing in adults: what is it and why is it performed?

A hydrogen breath test is a safe, easy-to-perform, 2-to 3-hour outpatient procedure used to identify the presence of small intestine bacterial overgrowth, evaluate carbohydrate maldigestion or malabsorption, and measure intestinal transit time. Breath sample analysis can reveal bacterial overgrowth in the small intestine by the characteristic early rise in breath hydrogen concentration (i.e., an earlier-than-expected rise at approximately 90 minutes when the substrate reaches the colon). Patients with irritable bowel syndrome are often referred for a hydrogen breath test because of symptoms of abdominal bloating, cramping, and diarrhea that are also characteristic of bacterial overgrowth. The elderly are at greater risk for nutritional compromise from untreated small intestine bacterial overgrowth than are younger patients. Treatment often consists of one or more courses of antibiotics. Most patients experience a reduction in symptoms with treatment.