Urinary bile acids in late pregnancy and in recurrent cholestasis of pregnancy

The metabolic profiles of urinary bile acids in pregnant women in the last trimester and patients with recurrent intrahepatic cholestasis of pregnancy (RCP) were studied. Following separation according to mode of conjugation, about thirty different bile acids were quantitatively analysed by gas chromatography-mass spectrometry. In all patients the sulphate fraction comprised 50--90% of the total bile acids. In RCP a shift from glycine to taurine conjugation was noted to together with a slight relative increase in sulphation. A ten- to hundred-fold increase in cholic and chenodeoxycholic acids was seen in RCP, the increase being mainly in the sulphate fraction. Tetrahydroxylated bile acids, tentatively regarded as 1- and 6-hydroxylated products of cholic acid, were quantitatively important in patients with RCP. The relative amounts of the secondary bile acids, deoxycholic and lithocholic acids, decreased with increasing cholestasis. Metabolites hydroxylated at C-6 were common, and the excretion of hydroxylated at C-6 were common, and the excretion of hyocholic acid was positively correlated to that of chenodeoxycholic acid. An increase in the excretion of 5 alpha-configurated bile acids in RCP was noted. A positive correlation between the excretion of 3 beta-hydroxy-5-cholenoic acid and 3 beta,12 alpha-dihydroxy-5-cholenoic acid indicates a metabolic relationship between the two compounds. Because of the relatively small amounts of lithocholic and 3 beta-hydroxy-5-cholenoic acids in patients with RCP, these compounds do not seem to be of pathogenetic importance in this type of cholestasis.