Breath tests for functional gastrointestinal disorders: When and for what?

Breath tests (BTs) have long been used as a valuable diagnostic tool in medicine. Their longevity in the diagnostic realm is likely due to the following advantages: they are noninvasive, easy to perform, and capable of repetitive testing. BTs have a variety of indications and have been used to explore the pathophysiology of functional gastrointestinal disorders (FGIDs). Hydrogen and methane BTs are often used to evaluate FGIDs but have several caveats to its methodology and interpretation. The recent release of the North American consensus guidelines provides uniformity to these BTs in attempts to provide standardization. This review explores the role of methane/hydrogen and also gastric emptying carbon-13 BTs in FGIDs, specifically irritable bowel syndrome (IBS), IBS-like symptoms, and functional dyspepsia. We review the role of BTs in FGIDs and how they not only provide diagnostic information, but the pathophysiologic mechanisms that drive these disorders. This, ultimately, can provide guided treatment for these disorders that at times can be difficult to manage.