Practical application of breath tests in disorders of gut-brain interaction.

Frequently occurring diseases of disordered gut-brain interactions are the irritable bowel syndrome and functional dyspepsia. Breath tests are noninvasive and are used to monitor a variety of gastrointestinal functions or conditions. Their general principle is the oral application of a test substance, the metabolism of which results in a substrate that can be measured in expiratory air. Clinically used breath tests use carbohydrates or stable 13C-enriched substrates. This review will focus on two questions, which breath tests are relevant for initiating treatments and which breath tests are useful for assessing treatment response? Recently published guidelines have described breath tests in detail and the recommendations for their use will be based on recommendations of these guidelines.