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

Idiopathic bile acid malabsorption is a poorly recognized cause of chronic diarrhoea. The SeHCAT (75Selenium HomotauroCholic Acid Test) can accurately diagnose this condition.

To identify patients with idiopathic bile acid malabsorption, to describe their clinical features, both qualitatively and quantitatively, and to assess the response to cholestyramine.

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.

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.

Idiopathic bile acid malabsorption, once suspected, especially by documenting true 'large volume' watery diarrhoea or 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.