Normal or increased bile acid uptake in isolated mucosa from patients with bile acid malabsorption

Introduction Bile acid malabsorption as reflected by an abnormal Se-75-labelled homocholic acid-taurine (75 SeHCAT) test is associated with diarrhoea, but the mechanisms and cause-and-effect relations are unclear Objectives Primarily, to determine whether there is a reduced active bile acid uptake in the terminal ileum in patients with bile acid malabsorption. Secondarily, to study the linkage between bile acid malabsorption and hepatic bile acid synthesis. Methods Heal biopsies were taken from patients with diarrhoea and from controls with normal bowel habits. Maximal active bile acid uptake was assessed in ileal biopsies using a previously validated technique based on uptake of C-14-labelled taurocholate. To monitor the hepatic synthesis, 7 alpha-hydroxy-4-cholesten-3-one, a bile acid precursor, was assayed in blood. The (SeH)-Se-75 CAT- retention test was used to diagnose bile acid malabsorption. Results The taurocholate uptake in specimens from diarrhoea patients was higher compared with the controls [median, 77 (n=53) vs 6.1 mu mol/g per min (n=17)] (P < 0.01) but no difference was seen between those with bile acid malabsorption (n=18) versus diarrhoea with a normal (75)SeHCAT test (n=23). The 75 SeHCAT values and 7 alpha-hydroxy-4-cholesten-3-one were inversely correlated. Conclusions The data do not support bile acid malabsorption being due to a reduced active bile acid uptake capacity in the terminal ileum.