Fetal Bile Acid Metabolism: Analysis of Urinary 3β-Monohydroxy-Δ5 Bile Acid in Preterm Infants

Abstract

To elucidate the urinary concentration of total bile acids after birth and the profile of the usual and unusual urinary bile acids, especially 3β-hydroxy-5-cholen-24-oic acid (Δ⁵-3β-ol), we measured the concentrations of 13 bile acids in the urine from preterm infants vs. full-term controls by gas chromatography-mass spectrometry. The urinary concentration of total bile acids in early preterm infants below 32 weeks of gestational age significantly exceeded that of the late preterm and full-term infants (p < 0.0005). The major urinary bile acids in early preterm infants were cholic acid, 1β,3α,7α,12α-tetrahydroxy-5β-cholan-24-oic acid and Δ⁵-3β-ol. In conclusion, the high urinary concentrations of total bile acids in preterm infants may be due to an overproduction, or more likely to a low hepatic bile acid clearance. An alternative fetal pathway, the acidic pathway, may be a major route of bile acid biosynthesis in preterm infants.