The Bilirubin Binding Panel: A Henderson-Hasselbalch Approach to Neonatal Hyperbilirubinemia

摘要

Poor plasma bilirubin binding increases the risk of bilirubin neurotoxicity in newborns with hyperbilirubinemia. New laboratory tests may soon make it possible to obtain a complete bilirubin binding panel when evaluating these babies. The 3 measured components of the panel are the plasma total bilirubin concentration (B-Total), which is currently used to guide clinical care; the bilirubin binding capacity (BBC); and the concentration of non-albumin bound or free bilirubin (B-Free). The fourth component is the bilirubin-albumin equilibrium dissociation constant, K-D, which is calculated from B-Total, BBC, and B-Free. The bilirubin binding panel is comparable to the panel of components used in the Henderson-Hasselbalch approach to acidbase assessment. Bilirubin binding population parameters (not prospective studies to determine whether the new bilirubin binding panel components are better predictors of bilirubin neurotoxicity than B-Total) are needed to expedite the clinical use of bilirubin binding. At any B-Total, the B-Free and the relative risk of bilirubin neurotoxicity increase as the K-D/BBC ratio increases (ie, bilirubin binding worsens). Comparing the K-D/BBC ratio of newborns with B-Total of concern with that typical for the population helps determine whether the risk of bilirubin neurotoxicity varies significantly from the inherent risk at that B-Total. Furthermore, the bilirubin binding panel individualizes care because it helps to determine how aggressive intervention should be at any B-Total, irrespective of whether it is above or below established B-Total guidelines. The bilirubin binding panel may reduce anxiety, costs, unnecessary treatment, and the likelihood of undetected bilirubin neurotoxicity.