Increased Fecal Bile Acid Excretion in a Significant Subset of Patients with Other Inflammatory Diarrheal Diseases

Background: Increased fecal bile acid excretion (IBAX) occurs in a third of patients with functional diarrhea. Aims: To assess the prevalence of IBAX in benign inflammatory intestinal and colonic diseases presenting with chronic diarrhea. Methods: All patients with known inflammatory diseases or resections who underwent 48 h fecal fat and BA testing for chronic diarrhea at a single center were included. Quiescent disease was based on clinical evaluation and serum, endoscopic and imaging studies. IBAX was defined by: > 2337 µmol total BA/48 h; or primary fecal BAs > 10%; or > 4% primary BA plus > 1000 µmol total BA /48 h. Demographics, fecal weight, fecal fat, stool frequency and consistency were collected. Nonparametric statistical analyses were used for group comparisons. Results: Sixty patients had celiac disease (51 quiescent, 9 active), 66 microscopic colitis (MC: 34 collagenous, 32 lymphocytic), 18 ulcerative colitis (UC), and 47 Crohn’s disease (CD). Overall, fecal fat, 48 h stool weight, frequency and consistency were not different among subgroups except for inflammatory bowel disease (IBD) based on disease location. Almost 50% patients with celiac disease and MC had IBAX, with a greater proportion with increased primary fecal BA. Among UC patients, rates of IBAX were higher with pancolonic disease. A high proportion of patients with ileal resection or CD affecting ileum or colon had IBAX. IBAX was present even with quiescent inflammation in UC or CD. Conclusions: A significant subset of patients with MC, quiescent celiac disease and IBD had increased fecal BA excretion, a potential additional therapeutic target for persistent diarrhea.