Altered metabolism of bile alcohol and bile acid in complete extrahepatic cholestasis: qualitative and quantitative aspects.

Urinary excretion of bile alcohols and bile acids in patients with complete extrahepatic cholestasis before and after the release by external biliary drainage was studied. Following extraction, isolation, and hydrolysis, bile alcohols were determined by capillary gas-liquid chromatography-mass spectrometry as dimethylethylsilyl derivatives. During cholestasis, 8.89 mumol/day of bile alcohol and 140.4 mumol/day of bile acid were excreted in urine. The amount of bile alcohol excreted was 6.1% of that of bile acid. Positive correlation between excretion of bile alcohols and bile acids was observed. The major bile alcohols excreted were also present in urine from healthy individuals but in much smaller amounts. After the release of extrahepatic cholestasis, urinary excretion of bile acid decreased rapidly, but that of bile alcohol decreased only gradually. The latter often increased again and remained high. The results indicate that the increased excretion of bile alcohols in complete extrahepatic cholestasis may reflect the expansion of a normally existing pathway of bile alcohol synthesis and excretion leading to the modification of bile alcohols for their efficient urinary elimination. It is also suggested that the rate of synthesis of bile alcohols is determined partly by the size of the substrate pool available.