[Retrograde ileal bile acid tolerance test--experimental and clinical study].

Oral bile acid tolerance test has been used to detect a functional impairment of the small intestine in Crohn's disease. The damage should be strongly expressed in the terminal ileum because of preferential involvement, therefore, we devised the retrograde ileal bile acid tolerance test, where bile acid was administered into closed segment of the terminal ileum using a 4 lumen double balloon tube through a colonoscope. In basic experiment using dogs with or without experimentally induced ileitis by trinitrobenzene sulfonic acid, ursodeoxycholic acid (UDCA) solution of several concentrations was given into the duodenum (corresponding to oral test) or the terminal ileum. Plasma was collected for 60 min at given time points, and then plasma total bile acid level (TBA) and bile acid fraction were measured. In a clinical study, both oral test and retrograde ileal bile acid tolerance test were carried out in 5 cases of Crohn's disease with ileitis and 6 healthy control subjects. Plasma was collected for 30 min after ileal loading of 30 ml UDCA solution (10 mg/ml). In oral bile acid tolerance test, plasma was collected for 180 min after taking 600 mg of UDCA. Basic experiments in dogs showed: 1) TBA was increased in proportion to dose of UDCA loaded in the intact ileum. 2) Absorption of bile acid after ileal loading of UDCA was significantly suppressed in experimentally induced ileitis, whereas no difference was observed after duodenal loading of UDCA. Clinical study in human subjects showed; 1) Absorption of bile acid after ileal loading of UDCA was significantly suppressed in Crohn's disease, compared with controls. 2) Examination of bile acid fraction showed that more than 90% of bile acid increased in serum after ileal loading of UDCA was free type UDCA. These findings indicated that retrograde ileal bile acid tolerance test is useful for an accurate evaluation on absorptive function in the ileum.