Hydrogen breath test

A hydrogen breath test (or HBT) is used as a clinical medical diagnosis for people with irritable bowel syndrome, and common food intolerances. The test is simple, non-invasive, and is performed after a short period of fasting (typically 8 hours).

Additional recommended knowledge

Weighing the right way

Essential Laboratory Skills Guide

Safe Weighing Range Ensures Accurate Results

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 / or sorbitol (typically 20 to 25 g), and then required to take readings every 15 to 30 minutes for two to three hours. If the level of hydrogen rises to 20 points or more above the base reading, and is sustained for at least two readings, then the patient has fructose malabsorption.

Lactose intolerance - the patient takes a base reading of hydrogen levels in his/her breath. The patient is then given a small amount of pure lactose (typically 20 to 25 g), and then required to take readings every 15 to 30 minutes for two to three hours. If the level of hydrogen rises to 20 points or more above the base reading, and is sustained for at least two readings, then the patient has lactose intolerance. A particular spike pattern is required to be diagnosed with lactose intolerance, with the earlier spike caused by the bacteria in the small intestine and a later one caused by the bacteria in the colon.

The excess hydrogen is typically caused by an overgrowth of otherwise normal intestinal bacteria.