Hydrogen breath test

A hydrogen breath test (or HBT) is used as a diagnostic tool for small intestinal bacterial overgrowth and carbohydrate malabsorption, such as lactose, fructose, and sorbitol malabsorption. The test is simple, non-invasive, and is performed after a short period of fasting (typically 8–12 hours). Even though the test is normally known as a "Hydrogen Breath Test" some physicians may also test for methane in addition to hydrogen. Many studies have shown that some patients (approximately 35% or more) do not produce hydrogen but actually produce methane. Some patients produce a combination of the two gases. Other patients, who are known as "Non-Responders", don't produce any gas; it has not yet been determined whether they may actually produce another gas. In addition to hydrogen and methane, some facilities also utilize carbon dioxide (CO₂) in the patients' breath to determine if the breath samples that are being analyzed are not contaminated (either with room air or bronchial dead space air).

Testing may be administered at hospitals, clinics, physician offices or if the physician/laboratory has the proper equipment and breath collection kit, patients can collect samples at home to then be mailed in for analysis.

Tests vary from country to country, so the following information is provided as a rough guide to typical uses of the hydrogen breath test:

Fructose malabsorption – the patient takes a base reading of hydrogen levels in his/her breath. The patient is then given a small amount of fructose, and then required to take readings every 15, 30 or 60 minutes for two to three hours. The basis of the test is a failure to absorb the given sugar, which is then metabolized by bacteria that give off either hydrogen or methane. Therefore, the more gas that is produced, the less absorption has occurred. If the level of hydrogen rises above 20 ppm (parts per million) over the lowest preceding value within the test period, the patient is typically diagnosed as a fructose malabsorber. If the patient produces methane then the parts per million for the methane typically rises 12 ppm over the lowest preceding value to be considered positive. If the patient produces both hydrogen and methane then the values are typically added together and the mean of the numbers is used to determine positive results, usually 15 ppm over the lowest preceding value.

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Wikipedia