Neonatal jaundice: physiologic variation or pathologic process.

Neonatal hyperbilirubinemia and jaundice affect approximately 60% of the 4 million newborns in the United States each year. Jaundice results from bilirubin deposition in the skin and mucous membranes, becoming clinically visible at a serum bilirubin level of 5 to 7 mg/dL. At a higher but undefined level, bilirubin may deposit in the brain where it can cause transient dysfunction or permanent neurologic impairment.