Kinetics and pool size of chenodeoxycholic acid in cholesterol gallstone patients

The pool size, half life, and daily production rate of chenodeoxycholic acid (CDCA) was determined by the isotope dilution method upon intravenous injections of about 10 muCI OF 24-14C-CDCA in 7 patients with radiolucent gallstones in functioning gallbladders, and 9 healthy controls. Bile was obtained by duodenal intubation. The method also allowed measurement of the CDCA percentage of total bile acids (TBA) and an indirect calculation of the TBA pool size. The pool size and daily production rate of CDCA were slightly, but not significantly, diminished in the gallstone patients. The half life of CDCA was almost equal in the 2 groups. The CDCA percentage of TBA was significantly higher in the gallstone patients (0.02 less than P less than 0.05), and the TBA pool size was significantly reduced (P less than 0.01) in the gallstone patients. It is concluded that the CDCA metabolism is similar to that of cholic acid in gallstone patients. Thus the formation of gallstones is hardly due to specific alterations in CDCA metabolism, suspected on account of the specific cholelitholytic effect of CDCA ingestion. The significance of increased CDCA percentage in bile is discussed in relation to the results from other study groups, and it is pointed out that a relative increase in the bile content of dihydroxy bile acids may lead to reduced cholesterol holding capacity of bile, and thus favor the formation of gallstones.