The formation and metabolism of 3 ,7 -dihydroxy-5 -cholestan-26-oic acid in man.

The formation and metabolism of a naturally occurring C(27) bile acid, 3alpha,7alpha-dihydroxy-5beta-cholestan-26-oic acid, was studied in patients with T-tube bile fistulas. C-26-cholesterol-(14)C was shown to be converted to this C(27) bile acid. After synthesis and labeling with tritium, 3alpha,7alpha-dihydroxy-5beta-cholestan-26-oic acid was efficiently metabolized to chenodeoxycholic acid. After oral and i.v. administration there was conversion of about 80% of the administered amount to chenodeoxycholic acid. A small amount, less than 2% of the administered radioactivity, was converted to cholic acid. The remainder of the radioactivity was excreted in two unidentified peaks of radioactivity. The results of this study demonstrate that 3alpha,7alpha-dihydroxy-5beta-cholestan-26-oic acid is a metabolic product of cholesterol and is further metabolized, predominantly to chenodeoxycholic acid and to a minor extent to cholic acid in man.