Primary bile acid malabsorption: a pathophysiologic and clinical entity?

Primary bile acid malabsorption is defined as chronic diarrhoea with bile acid malabsorption of unknown cause and a symptomatic response to cholestyramine. Convincing evidence of the proposed pathophysiology--a defect of the active bile acid absorption in the distal ileum--has never been substantiated. We found no evidence of a bile acid transport defect across the ileal brush border membrane in 10 patients with primary bile acid malabsorption; moreover, transport was significantly higher than in a control group. In the patients with primary bile acid malabsorption the estimated bile acid pool was significantly larger than in a control group and in a group of patients with ileal disease. In addition, the oro-anal transit time of radiopaque markers was shorter in the primary bile acid malabsorption group than in both other groups. This suggests that the bile acid pool size as well as intestinal motility could play a role in the pathophysiology of primary bile acid malabsorption.