Definition: The hydrogen breath test (HBT) is used to diagnose the presence of an intolerance to dietary sugars, such as lactose, fructose or sorbitol. The testing begins by having the patient drink a solution made up of the suspected substance. If an intolerance exists, i.e., the individual does not digest the sugar in the small intestine, the substance will make its way to the large intestine and be fermented by bacteria in the colon. The by-product of this fermentation is hydrogen, which is then measured through the use of a breath test administered several hours after the ingestion of the suspected substance. If no such intolerance exists, the substance is thought to be digested in the small intestine, and there is no rise in breath hydrogen upon testing.
Related information: Small Intestine Bacteria Overgrowth (SIBO)
Also Known As: HBT
