Hydrogen breath tests

Modern, non-invasive functional diagnostics in gastroenterology includes a number of breath tests based on measuring the concentration of hydrogen in exhaled air. The concentration of hydrogen H2 in the exhaled air increases in direct proportion to the hydrolysis of the administered substrate. After administration of the test substrate, exhaled air samples are taken and the hydrogen concentration is determined by gas chromatography or using very simple hand-held, battery analyzers (H2-monitors) with an electrochemical sensor, which are routinely used in pediatrics in differential diagnosis of malabsorption syndrome. Lactose may be a suitable substrate (for the diagnosis of lactose intolerance), sucrose, sorbitol, fructose, glucose or even D-xylose, which was previously commonly used for the D-xylose absorption test.

The applications of hydrogen breath tests cover a wide area. In addition to the mentioned differential diagnosis of malabsorption syndrome, it is the syndrome of bacterial overgrowth in the small intestine (SBBO, the substrate is for example D-xylose), determination of gastrointestinal motility, orocecal transit time (OCCT, substrate is for example inulin) - small bowel transit time (SBTT) also referred to as LHBT (the substrate provided is lactulose), or the quality of the colon preparation before endoscopic examination. The gastrointestinal passage time is an important data for the evaluation and interpretation of other functional tests, and is therefore often combined with other breath tests, for example 13C/H2 - lactose test, which evaluates the enzymatic cleavage of lactose (the marker is carbon 13C) and at the same time as a correction of motility, passage is used bacterial cleavage in the large intestine (the marker is H2).