Serum bile acids in newborns and children.

A specific and sensitive radioimmunoassay for cholic, chenodeoxycholic, and lithocholic acid conjugates and for sulfolithocholylglycine was used to measure serum bile acids (BA) in infants and children. Elevated cholic and chenodeoxycholic acid values were observed in the first year of life in fasting infants. Newborn babies presented high levels of primary BA not correlated with those of the mothers. In premature newborn babies who had not yet been fed, meal induced a considerable reduction in the primary BA levels in serum. In normally fed babies, meal induced a significant increase in the primary BA levels in serum. These data suggest a progressive maturity throughout the first year of life of the serum BA determinants, i.e., gallbladder emptying, intestinal motility and absorption, and hepatic uptake.