A Suggested Strategy for Approaching Unexplained Abdominal Bloating Using Glucose and Fructose Breath Testing

Introduction: Unexplained bloating is one of the most common and bothersome gastroenterology complaints. Bloating is likely to present in association with belching, flatulence, post-prandial distension, borborygmi, pain, and diarrhea. Patients with such symptoms are usually placed on a lactose and/or gluten free diet and if they do not improve they undergo blood and stool tests, imaging studies and endoscopic procedures to rule out organic etiologies. If this fails to diagnose the problem, then these patients are placed into the category of functional GI disorder. Small bowel bacterial overgrowth (SIBO) and dietary fructose intolerance (DFI) are responsible for bloating and other nonspecific GI symptoms. Their exact prevalence is unknown because they are poorly recognized an as a consequence poorly managed. This study attempts to investigate the usefulness of breath testing to identify SIBO and DFI in unexplained bloating patients. Methods: Since December 2012, we studied 257 patients referred to our motility center with unexplained abdominal bloating. They underwent glucose breath test (GBT) to assess for SIBO. GBT was performed after a 100 gm oral glucose load with breath sample collection at baseline and every 20 minutes for 3 hours to measure hydrogen and methane concentrations. A test was considered to be positive if the baseline or peak hydrogen concentrations during the study exceeded 20 parts per million (ppm), or methane level at baseline or latter peaked at > 10 ppm. Patients with a negative GBT were then recommended to undergo a fructose breath test (FBT) and 56 agreed to participate. FBT was performed after 25 gm fructose oral administration, Breath sampling and positive parameters were the same as described above. Results: 111 out of 257 patients (43%) were positive for SIBO by GBT. Subsequently, 26 out of 56 patients (46 %) (F: 48, mean age: 53) were found to have DFI with a positive FBT. The average time to a positive FBT was 91 min. Only one FBT was positive based on methane concentration, the rest had increased hydrogen concentrations. Conclusion: 1) GBT to exclude SIBO should be considered as the next step to evaluate unexplained abdominal bloating. 2) A negative GBT should then trigger a FBT to detect fructose intolerance since 46 % of negative GBT patients were found to be fructose intolerant. 3) Our data provides a diagnostic pathway to identify therapeutic targets for the challenging complaint of unexplained bloating.