Sucrase Isomaltase Deficiency (SID) as a Potential Masquerader in Irritable Bowel Syndrome (IBS)

Abstract

Introduction: Patients with IBS frequently have meal-related symptoms. A lactose-free diet or a low FODMAP diet is often recommended to patients and can effectively reduce the symptoms. However, the incidence of SID, is less well-defined in the adult population. Emerging evidence has correlated genetic polymorphisms in the SI complex with IBS-D/M. The aim of this study was to determine the frequency of SID in adults with symptoms of diarrhea and bloating in a consecutive cohort of patients with presumed diagnosis of IBS-D/M who had upper endoscopies performed for the evaluation of chronic diarrhea. A secondary aim was to compare the OR of having symptoms of diarrhea, bloating and abdominal pain in those with SID compared to those without SID. Methods: All patients with presumed diagnosis of IBS-D/M or chronic diarrhea who underwent testing for disaccharidase deficiency by duodenal biopsy between July 2016 to May 2017 were included. Patients with other gastrointestinal disease were excluded. Results: A total of 29 patients (females: 17, males: 12) were included. Based on disaccharidase testing, we found +SID in 34% of all patients. Among patients who tested positive for SID, 60% had diarrhea, 40% had abdominal pain, and 40% complained of bloating. In comparing patients with SID vs normal enzymatic activity, the OR of abdominal pain was statistically significant and found less commonly in patients with SID than those without, OR=0.14 (CI 0.01-0.96, p=0.03), while the OR of having diarrhea was 2.48 (CI 0.42-16.75, p=0.27) and that of bloating was 0.40 (CI 0.06-2.40, p=0.27). Both of the later did not reach statistical significance. Although diarrhea was more commonly found in patients with SID, given our small sample size, the above findings are not sufficient to conclude that diarrhea is more commonly seen in patients with SID. Also an interesting was the finding of concomitant lactase deficiency (n=18) in 100% of patients with sucrase enzyme deficiency (n=10). Conclusion: Sucrase maldigestion, should be considered in patients with chronic diarrhea but perhaps not necessarily in those with IBS-D/M as our findings surprisingly showed abdominal pain to be less frequently seen in those with SID. Bloating was also less frequent in those with SID although this was not statistically significant. Future studies should be expanded on the clinical parameters in patients with SID and then determine if this subset of patients will respond to dietary modification and/or digestive enzyme (Sucraid®) replacement.