Study design

We retrospectively reviewed the results of fasting lactulose breath test performed at an open access motility lab at a tertiary care institution between 2013 and 2019. Indications that were reported in the study were recorded and correlated with available information per chart review. Age and gender were recorded for studies that showed methane‐elevation. Lactulose breath test: On the day before the test, patients were asked to consume a low carbohydrate diet without vegetables and fiber and to avoid dairy products. The test was performed after an overnight fast, and for the duration of the test patients were asked not to smoke or engage in any exercise. Antibiotics were stopped 2 weeks prior to the procedure and if tolerated by the patients, laxatives stopped 1 week prior to breath testing. After a baseline breath sample, 10 g of lactulose were consumed, followed by a cup of water, and samples were obtained every 30 min for a period of 150 min. Breath samples were collected in a bag (QuinTron Instrument Company, Inc.) and alveolar gas was analyzed for both H₂ and CH₄ levels by chromatography (QuinTron Micro Analyzer, QuinTron Instrument Company, Inc.).