[Primary bile acid diarrhea in a community gastroenterology practice]

When first described in 1976, primary bile acid diarrhea (BAD Type 1) was regarded as a very rare cause of chronic diarrhea. Today, the incidence is estimated as > 1 %. Availability of diagnostic tools varies widely and, in Germany, there is no generally consented recommendation for their use. BAD is still widely underdiagnosed.Since the beginning of the '90 s, we have added a therapeutic trial with cholestyramine to our diagnostic approach of chronic diarrhea. Patients with a positive test were offered a Selenium-homocholic acid taurine (SeHCAT) test for confirmation of bile-acid-diarrhea (BAD), using a 7-day-retention of 20 % as cut-off value.From April 1991 to March 2017, after exclusion of other relevant causes for chronic diarrhea like IBD, celiac disease or microscopic colitis, 70 patients with a positive trial treatment of cholestyramine were identified for evaluation. Sixty of them had a SeHCAT test. Patients with BAD Type 1 and Type 3 were excluded, except for cholecystectomy.85 % (35/41) of patients with BAD Type 1 needed continued medical treatment (median follow-up time 8.3 (1 - 23.6) years). Among them, 68.6 % (24/35) took cholestyramine, 31.4 % (11/35) loperamide or another antidiarrheal treatment. 14.6 % (6/41) of patients reported a spontaneous remission after median 2.9 (0.7 - 5.7) years.In the group of patients with BAD after cholecystectomy, 82 % (8/11) still needed treatment after median 7.7 (1 - 24.5) years; 8 having taken cholestyramine, one patient nothing and two with spontaneous remissions.All (8/8) patients with a normal SeHCAT test (7-day retention > 20 %) had spontaneous relief after median 3.6 (1.2 - 6.3) months.Also, 70 % (7/10) of patients who had not been confirmed by the SeHCAT test still needed treatment after median 4.3 (3.7 - 18.3) years.Based on a trial treatment alone, diagnosis of BAD is possible but not assured. Due to its ubiquitous availability, it should be used consequently if other methods are not available. Despite the well-known shortcomings of cholestyramine, a therapeutic trial should be used more consequently. According to the current literature, using the SeHCAT test in the first place will give significantly better results and unnecessary follow-up examinations can be avoided. However, therapeutic consequences might be modest due to the well-known limitations of cholestyramine. A well-tolerated and licensed alternative to cholestyramine is urgently needed.