The hydrogen breath test is an office-based test that measures the hydrogen and methane levels detected in the breath of a patient. This allows the gastroenterologist to help determine the presence of small intestinal bacterial overgrowth (SIBO). The small bowel normally does not have large amounts of bacteria, however, with some patients, bacteria tend to colonize within the small bowel, causing symptoms such as bloating, flatulence, abdominal pain/discomfort, diarrhea and abdominal distension.

This test starts with the patient giving a baseline breath sample for testing for the levels of hydrogen and methane. After the baseline levels are determined, the patient drinks a solution with lactulose, a non-absorbable sugar. Afterwards, the patient gives seven more breath samples every fifteen minute interval. If there is a sharp increase of hydrogen or methane detected in the breath, the test is positive and the patient can be treated for SIBO. The hydrogen breath test takes approximately 90 minutes.

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