Glucuronides of unconjugated 6-hydroxylated bile acids in urine of a patient with malabsorption

Abstract

The excretion of bile acids in urine from a patient with chronic malabsorption was investigated. Bile acids were separated according to mode of conjugation using a lipophilic anion exchanger, diethylaminohydroxypropyl Sephadex LH-20. Following hydrolysis, individual bile acids were analyzed by computerized GC/MS. In addition, bile acid glucuronides were isolated and their methyl ester trimethylsilyl ether derivatives were directly analyzed by GC/MS. The patient had a normal or slightly increased excretion of bile acids in urine. Bile acids carrying a hydroxyl group at C-6 constituted about 40% of the total. Tetrahydroxylated bile acids were present which have not been found in healthy subjects. Glucuronides of otherwise unconjugated bile acids accounted for 20% of the total. About 90% of these conjugates were 6-hydroxylated, hyodeoxycholic acid being the major bile acid. It is suggested that a specific abnormality of bile acid metabolism is related to the disease in this patient.