Effects of ursodeoxycholic acid on conjugated bile acids and progesterone metabolites in serum and urine of patients with intrahepatic cholestasis of pregnancy

Background/Aims and Methods: The mechanism(s) behind the effects of ursodeoxycholic acid on serum steroid sulphate profiles in patients with intrahepatic cholestasis of pregnancy is not clear. Conjugated progestone metabolites and bile acids have therefore been analyzed in serum and urine of patients with intrahepatic cholestasis of pregnancy before and during treatment with ursodeoxycholic acid using chromatographic and mass spectrometric methods.Results: The concentration of glycine-/taurine-conjugated bile acids decreased from 8.9±3μmol/l (mean± SEM) before treatment to 1.8±0.6 sml/l during treatment with ursodeoxycholic acid. The total bile acid excretion in urine decreased from 56±14 to 32±5.6 μmol/g creatinine. The proportion of cholic acid in serum and urine, and of 1β-, 2β- and 6α-hydroxylated cholic acids in urine decreased markedly during ursodeoxycholic acid while the percentages of 3α, 12α-dihydroxy-3-oxo-4-cholenoic acid and chenodeoxycholic acid were unchanged. The levels in serum and excretion in urine of sulphated steroids decreased during ursodoexycholic acid, by 45–49% for disuphates and 33–35% for monosulphates. The ratios of 3α- to 3β-hydroxysteroid disulphates were lowered by ursodeoxycholic acid from 1.1 (mean) to 0.68 in serum, and from 1.2 to 0.70 in urine. The corresponding ratios for monosulphates before the during ursodeoxycholic acid were 6.9 and 4.5, respectively, in serum, and 21 and 5.2 respectively, in urine. The major monosulphates in urine, dominated by 5α-pregnane-3α, 20α-diol, were also conjugated with N-acetylglucosamine. The excretion of these double conjugates decreased from 27±8.4 to 15±5.3 μmol/g creatinine during ursodoexycholic acid. In contrast to suplhated steroids, the concentrations of glucruronides were unchanged in serum and their excretion in urine tended to increase during ursodeoxycholic acid. The metabolism of ursodeoxycholic acid was similar to that described in nonpregnant subjects. In addition to metabolites hydroxylated in the 1β-, 5β-, 6αβ and 22-positions, a 4-hydroxy-ursodeoxycholic acid was tentatively identified. This occurred predominantly as a double conjugate with glucine/taurine and glucuronic acid, as did other 4-hydroxylated bile acids of probable foetal origin.Conclusions: The results are compatible with the contention that ursodeoxycholic acid stimulates the biliary excretion of sulphated progesterone metabolites, particularly those with a 3α-hydroxy-5α(H) configuration and disulphates. The effects(s) appears to be independent of the stimulation of bile acid secretion. An effect of ursodeoxycholic acid on the reductive metabolism of progesterone cannot be excluded.