Idiopathic bile acid malabsorption: qualitative and quantitative clinical features and response to cholestyramine

Background: Idiopathic bile acid malabsorption is a poorly recognized cause of chronic diarrhoea. The SeHCAT ((75)Selenium HomotauroCholic Acid Test) can accurately diagnose this condition. Aim: To identify patients with idiopathic bile acid malabsorption, to describe their clinical features, both qualitatively and quantitatively, and to assess the response to cholestyramine, Method: Idiopathic bile acid malabsorption was considered in all patients complaining of chronic diarrhoea. They were included in the study if their SeHCATs were positive (< 15% retention) and secondary causes of bile acid malabsorption were excluded. The response to therapy with cholestyramine was assessed. Results: Nine patients were diagnosed with idiopathic bile acid malabsorption (median SeHCAT retention 8%, range 3-12.6), Their median daily faecal weight was 285 g (range 85-676) and median faecal fat output was 17 mmol/24 h (range 8.3-38.8), Six patients had an immediate response to cholestyramine. There was a marked reduction in stool frequency (median stool frequency pre-treatment 5/day vs, 2/day post-treatment, P = 0.03). Five patients had large volume diarrhoea (faecal weight > 200 g/day) and three had steatorrhoea, Conclusions: Idiopathic bile acid malabsorption, once suspected, especially by documenting true 'large volume' watery diarrhoea pr steatorrhoea, is easily diagnosed and response to therapy is often very good, There is often a previous history of gastrointestinal infection and this condition should be considered in patients with chronic diarrhoea of undetermined origin, especially before they are labelled as having irritable bowel syndrome.