Cholic acid and chenodeoxycholic acid concentrations in serum during infancy and childhood.

Concentrations of two primary bile acids (cholic and chenodeoxycholic acids) were determined by radioimmunoassay in the serum of infants and children at ages ranging from 1 hour to 15 years. The same bile acids were also measured in umbilical cord serum. Concentrations of the primary bile acids were significantly higher in the serum of 1-hour old infants than those in the umbilical cord serum or the peripheral vein serum of adults. The levels of cholic and chenodeoxycholic acid remained high until the age of 6 months, being about 5-fold higher than those in the sera of adults. Primary bile acid concentrations reached the adult level by the age of 1-2 years. These results indicate that developmental changes occur in the metabolism and excretion of bile acids in man. The relatively high concentrations of the primary bile acids in serum during the first 6 months of life suggest that up to this age, the mature ability of the liver to excrete the bile salts into the bile and/or to clear them from the circulation has not yet been reached.