Prevalence of Bile Acid Diarrhea and Effect of Budesonide on the Bile Acid Homeostasis in Flare of Microscopic Colitis

Background and Aims: Microscopic colitis (MC) and bile acid diarrhea (BAD) are common causes of chronic watery diarrhea. Retrospective studies suggest that BAD coexists in a subset of patients with MC, but the interplay and therapeutic implications remain unclear. We aimed to determine the prevalence of BAD in patients with an MC flare using biochemical markers, to assess the effects of budesonide on BAD biomarkers, and to correlate with clinical outcomes. Methods: In this prospective multicenter study conducted at 3 Danish secondary care outpatient clinics, 49 patients with an MC flare were treated with budesonide for 6 weeks. 7α-hydroxy-4-cholesten-3-one (C4) levels ≥46 ng/mL defined BAD. C4 allows timely testing but has 47% sensitivity. Fecal bile acids (BAs) and fibroblast growth factor 19, stool habits, and quality of life were evaluated. Results: BAD was diagnosed in 6 (12%; 95% confidence interval, 5%–25%) of 49 patients (C4 range 47–92 ng/mL). Three patients had a gray zone C4 between 33 and 46 ng/mL. Patients with BAD had lower fibroblast growth factor 19 and high levels of primary and total BA in spot stool samples. Budesonide significantly reduced diarrhea and improved health-related quality of life in all patients. In patients with BAD, budesonide normalized stool BA, but C4 levels remained elevated. Conclusion: These data demonstrate that some patients with MC flare have BAD. In patients with MC and BAD, budesonide reduced diarrhea symptoms and normalized stool BA levels but did not improve an underlying dysregulation of BA homeostasis. Clinicians may consider testing for BAD in patients with recurrent MC. Trials on therapies targeting BAD in MC patients are warranted.