Usefulness of the bilirubin/albumin ratio for predicting bilirubin-induced neurotoxicity in premature infants

Unconjugated hyperbilirubinaemia occurs in almost all premature infants and is potentially neurotoxic. Treatment is based on total serum bilirubin (TSB), but treatment thresholds are not evidence based. Free bilirubin (Bf) - that is, not bound to albumin, seems a better parameter for bilirubin neurotoxicity, but measurements of Bf are not available in clinical practice. The bilirubin/albumin (B/A) ratio is considered a surrogate parameter for Bf and an interesting additional parameter in the management of hyperbilirubinaemia. This paper reviewed the evidence supporting the use of B/A ratios for predicting bilirubin-induced neurological dysfunction (BIND) including neurodevelopmental delay in jaundiced premature infants (gestational age less than 32 weeks). A literature search was performed and six publications reviewed regarding B/A ratios in the management and outcome of jaundiced premature infants. No prospective clinical trials had been undertaken to show whether bilirubin-induced neurotoxicity is reduced or whether unnecessary treatment is avoided by using the B/A ratio in addition to TSB. Recently, a randomised controlled trial evaluating the effect of the additional use of the B/A ratio on neurodevelopmental outcome in jaundiced premature infants has been initiated. Based on the prevailing evidence many authorities suggest that the additional use of the B/A ratio may be valuable when evaluating jaundiced premature infants.