Bilirubin pigments in the first meconium of newborn infants.

Objective: To determine the pattern of excretion of total bilirubin IXa and IXb in the first meconium of newborn infants. Methods: First two newborns of varying gestational age were selected every week through random sampling from the neonatal unit. Of the 41 newborn infants selected 8 expired before meconium passage, hence the results are from 33 newborns. Meconium was collected and stored at -20°C, protected by aluminium foil. Samples were defrosted, vortex mixed with equal amount of dimethyl-sulfoxide, centrifuged, and analyzed by HPLC. Results: Unconjugated Bilirubin-IXα and -IXβ were identified and quantitative estimation of Bilirubin-IXa done. Bilirubin-IXb was greater than 50% of the total, in the first meconium of the newborn. Amount of bilirubin excreted in meconium was 29.2 - 90.8 mg [0.051 - 0.155 mmol] per sample of meconium passed. Amount was 9.7 mg/ Kg of body weight in term newborn and 12 mg / kg in preterm. Conclusion: The amount of bilirubin -IXb decreases and bilirubin-IXa increases with increasing gestational age. Newborns with birth asphyxia (BA) had significantly greater quantity of bilirubin in meconium, compared to infants without BA.