Purpose of Technology: Hydrogen breath tests (HBTs) may be used to identify carbohydrate malabsorption by assessing changes in hydrogen expiration following the administration of lactose, fructose, or other carbohydrates. Carbohydrate malabsorption may be suspected in patients with symptoms suggestive of or a diagnosis of functional bowel disorders (FBDs), including irritable bowel disease. In these patients, HBTs may identify an underlying cause of the symptoms and thereby also potential treatments. However, the clinical utility and clinical validity of HBTs have not been firmly established.
Rationale: Lactose or fructose hydrogen breath test (LHBT or FHBT, respectively) results are obtained quickly compared with genotyping techniques and are comparatively safer and less costly than more invasive techniques.
Controversy: While breath tests are used widely in clinical and research settings, a lack of standardized approaches has yielded wildly variable diagnostic values. The tests are sensitive to several outside factors that serve as potential sources for false-positive HBT results (e.g., presence of oral flora at the time of the test, failure to adhere to a low-fiber diet the day before the test, rapid transit through the small intestine) and false-negative HBT results (presence of methanogenic bacteria in the intestine, delayed gastric emptying).
Relevant Questions:
- What is the clinical validity of HBTs for the detection of carbohydrate malabsorption in patients with irritable bowel syndrome (IBS) or other FBDs?
- What is the clinical utility of HBTs for the detection of carbohydrate malabsorption in patients with IBS or other FBDs?
- What are the harms associated with HBTs?
- Have definitive patient selection criteria been established?
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