Profile of urinary bile acids in infants and children: Developmental pattern of excretion of unsaturated ketonic bile acids and 7 beta-hydroxylated bile acids

Unusual bile acids, such as unsaturated ketonic and 7 beta- hydroxylated bi le acids, have been detected in urine early in life. To elucidate the norma l profiles of usual and unusual urinary bile acids in the neonatal and pedi atric periods, we measured the concentrations of 28 kinds in urine from nor mal newborns, infants, and children by gas chromatography-mass spectrometry . The mean total bile acid/Cr ratio in 7-d-old infants was significantly hi gher than in subjects of other age groups (birth, 2-4 mo, 5-7 mo, 11-12 mo, 2-3 y, 9-14 y, and adult) (p < 0.05). Relatively large amounts of unusual bile acids were detected during infancy, especially during the period up to 1 mo of age. At that time, 1 beta,3 alpha,7 alpha,12 alpha-tetrahydroxy-5 beta-cholan-24-oic, 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-chol-1-en-24-oi c, and 7 alpha,12 alpha-dihydroxy-3-oxo-4-cholen-24-oic acids were predomin ant among the unusual urinary bile acids present. Moreover, the levels of 3 alpha,7 beta,12 alpha-trihydroxy-5 beta-cholan-24-oic acid increased signi ficantly after 2-4 mo of age. These results indicate that bile acid synthes is and metabolism in the liver of developing infants are significantly diff erent from that occurring in the Liver of adults. Significant amounts of ur inary isomerized 7 beta-hydroxylated bile acids were detected after late in fancy, probably because of changes in the intestinal bacterial flora respon se to a change in nutrition. We describe, for the first time, evidence of t he epimerization of the 7 alpha-hydroxyl group of cholic acid, which may be unique to human development.