Fasting and postprandial serum bile acid concentration with special reference to variations in the conjugate profile

Serum bile acids were group-separated by ion exchange chromatography on diethylaminohydroxypropyl Sephadex LH-20 into unconjugated bile acids and bile acids conjugated with either glycine, taurine, glucuronic acid or sulphuric acid. The conjugate moiety was hydrolysed by treatment with a combination of Helix pomatia and cholylglycine hydrolase and the released bile acids analysed by gas liquid chromatography/mass spectrometry. Analysis of fasting and postprandial serum from six healthy subjects showed that, in addition to the primary bile acids, cholic (C) and chenodeoxycholic acid (CDC), secondary bile acids were present to varying extents. Unconjugated serum bile acids were found in four of the six subjects. Glycine and taurine conjugates of C and CDC and their glucuronides and sulphates were found in all subjects. The postprandial increase of serum bile acids was mainly due to increase of the glycine conjugates of C and CDC. After the meal, the ratio C:CDC in glycine and taurine conjugates shifted to lower values.