Bile acid metabolism in extrahepatic biliary atresia: lithocholic acid in stored dried blood collected at neonatal screening.

Lithocholic acid (LCA) is a potent hepatotoxic compound. Fetal LCA may have a role in the pathogenesis of neonatal cholestasis/extrahepatic biliary atresia (EHBA). Fetal liver efficiently hydroxylates LCA in several positions. This may represent a detox-ification mechanism. In the present study LCA, cholic acid (CA) and chenodeoxycholic acid (CDCA) were quantitated by gas chromatography-mass spectrometry using selected ion monitoring in small amounts of stored dried blood from six newborn infants with EHBA and fourteen con-trols. The blood was collected at neonatal metabolic screening. Mean blood levels (+/- S.E.M.) of LCA were 0.11 +/- 0.04 microM in the in-fants with EHBA and 0.08 +/- 0.02 microM in the control infants. The correspon-ding levels for CA and CDCA were 15.6 +/- 3.6 microM and 7.4 +/- 2.5 microM in the infants with EHBA and 1.7 +/- 0.3 microM and 1.8 +/- 0.4 microM in the controls. The increased levels of CA and CDCA in the infants with liver disease can be explained by cholestasis. The low blood levels of LCA indicate a normal fetal metabolism of this bile acid in EHBA.