Kinetics of primary bile acids in patients with non-operated Crohn's disease.

The metabolism of cholic acid and chenodeoxycholic acid was studied in seventeen patients with non-operated Crohn's disease, eleven ileitis and six ileocolitis patients. The turnover of cholic acid was significantly increased in patients with ileitis (k = 2.01 +/- 1.13 days-1; P less than 0.001) and ileocolitis (k = 0.91 +/- 0.47 days-1; P less than 0.005) as compared to normals (k = 0.35 +/- 0.19 days-1). Although chenodeoxycholic acid was better preserved in the enterohepatic circulation than cholic acid its turnover was also significantly faster in ileitis (k = 0.81 +/- 0.56 days-1; P less than 0.005) and ileocolitis patients (k = 0.62 +/- 0.18 days-1; P less than 0.01) than in normals (k = 0.20 +/- 0.09 days-1). The fractional turnover of cholic acid was related to the length of ileal involvement (r = 0.761; P less than 0.001; n = 17). Patients with Crohn's ileitis tended to preserve normal fasting total bile acid pools by increased synthesis of primary bile acids and efficient absorption of deoxycholic acid and ursodeoxycholic acid by the normal colon. Patients with active ileocolitis had decreased total fasting pool sizes (2.62 +/- 1.83 mmol; P less than 0.001) as compared to normals (7.69 +/- 1.61 mmol). In these patients there was no increase in bile acid synthesis as compared to normals and secondary bile acids were absent from bile. It is concluded that the colon has an important role in maintaining the fasting pool size to a normal level in the presence of an interrupted enterohepatic circulation of bile acids due to ileal disease.