Disorders of bilirubin binding to albumin and bilirubin-induced neurologic dysfunction.

Bilirubin-induced neurologic dysfunction (BIND) is a syndrome of subtle bilirubin neurotoxic disorders. The risk for developing BIND in newborns usually increases with elevated serum/plasma concentrations of unconjugated bilirubin. This risk is further increased by disorders of bilirubin binding to albumin, which includes a reduction in serum albumin concentrations or in the bilirubin-binding capacity and affinity of albumin, and the presence of displacing substances or infection. Serum unbound bilirubin (UB) concentration may be an ideal marker that reflects changes in bilirubin binding to albumin. Kernicterus, the chronic and with the most severe manifestations beyond BIND, is diagnosed by the presence of motor impairments with athetosis, abnormal magnetic resonance imaging, and/or brainstem auditory-evoked potential findings during infancy and childhood. Preterm infants sometimes have acute bilirubin encephalopathy without marked hyperbilirubinemia, such that bilirubin neurotoxicity occurs at bilirubin thresholds lower than usually associated with kernicterus. Disorders of bilirubin binding to albumin may be associated with the clinical signs of neurological injury associated with the lower bilirubin levels observed in preterm infants.