Physiologic - Production
Physiologic jaundice
Production
Utilizing CO excretion, it has been shown that bilirubin production in the neonate is increased to 8-10 mg/kg/day, 2-3 times the adult normal value. This is due to several different factors. First, the mean hemoglobin in newborns is 17-19 gm/dL, compared to 12-13 from 3 months to 12 years and 14-16 in adults. More importantly, the life span of the RBC in the term neonate is only 90 days compared to 120 days in adults; in preterms it may be as short as 75-80 days. So everyday the newborn is turning over a larger percentage of a bigger hemoglobin pool compared to adults. In addition, there may be increased turnover of RBC precursors and other heme proteins in newborns.The newborn has handicaps in more than one of the steps involved in bilirubin metabolism compared to adults. The most significant are production, conjugation and enteric recirculation. While the neonate also has deficiencies in bilirubin transport, uptake and excretion, these are not thought to be the primary factors involved in phsiologic jaundice.Return to top of page