C0279 - Prevalence of Disaccharidase Deficiencies in Adults With Irritable Bowel Syndrome and Functional Diarrhea: Interim Analysis From a Multicenter, Prospective U.S. Trial

Introduction: Disaccharidases are brush border enzymes that digest disaccharides to monosaccharides for absorption across the intestinal epithelium. Patients with disaccharidase deficiencies (DD) may experience post-prandial abdominal pain, bloating, flatulence, & diarrhea that can mimic Irritable Bowel Syndrome and diarrhea (IBS-D) & functional diarrhea (FD). While well-characterized in children, the prevalence of DDs in symptomatic adults is poorly defined.

Methods: In this ongoing study, adult ( >18 yrs) patients fulfilling Rome IV diagnostic criteria for IBS-D or FD were recruited at Michigan Medicine (UM) & the University of Texas Health Science Center at Houston (UTH). Exclusion criteria included pregnancy, lactation, severe GI or abdominal co-morbidities, & history of previous GI surgeries excluding cholecystectomy or appendectomy. Eligible patients completed upper endoscopy (EGD) with 2-4 small intestinal biopsies collected from the duodenum distal to the ampulla of Vater. Biopsy samples underwent disaccharidase assay to measure disaccharidase activity (normal sucrase: >28.0 µM/min/g, maltase: >120.8 µM/min/g, lactase: >15.4 µM/min/g, palatinase: >9.8 µM/min/g, glucoamylase: >13.1 µM/min/g) using validated protocols at experienced reference labs (Arnold Palmer Hospital Labs & Joli Diagnostics, Inc.).

Results: 154 patients (mean age = 45.6 yrs, 47% IBS-D, 53% FD, 74% female, 87% white) were enrolled & underwent EGD with biopsies collected to test for DD. More than a third of patients (56/154, 36.4%) had >1 DD. The most common DD was for lactase, found in 54 (35.1%) patients. Eleven patients (7.1%) tested positive for Sucrase-Isomaltase deficiency. Glucoamylase & palatinase deficiencies were each identified at 5%. Only lactase deficiency occurred in isolation. All patients with non-lactase deficiencies had other DDs, with at least 27% of these patients having pan-DDs (Table 1). The prevalence of the DDs were almost identical at both sites (Figure 1).

Discussion: More than 36% of US adult patients with IBS-D or FD had >1 DD. Lactase deficiency was the most common DD & the most likely to occur in isolation. Sucrase & maltase deficiencies were identified in approximately 1 in 14 symptomatic patients, & typically associated with at least 1 other DD. Lactase & non-lactase DD may be important & overlooked causes for symptoms in US patients with IBS-D or FD.