Bile pigments in humans and in nonhuman primates during the perinatal period: composition of meconium and gallbladder bile of newborns and adults.

Meconium of human infants and rhesus monkey infants (Macaca mulatta) contained only about 0.10 of the amount of bilirubin in gallbladder bile of the same individuals. Ninety-nine percent of the bilirubin in adult bile was conjugated. The proportion of conjugated bilirubin in infant bile and meconium was only slightly lower. Adult bile contained more bilirubin disconjugates than monoconjugates, whereas only 20% of the bilirubin in infant bile and meconium was in the form if disconjugates. The predominant azopigment in adult bile was azopigment delta (a glucuronide). Infant bile contained less azopigment delta, more azopigment alpha (azodipyrrole), and a so far unidentified conjugated azopigment (azopigment beta). Azopigment beta was also found in meconium but adult gallbladder bile contained only trace amounts of this pigment.