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Evaluation of unconjugated hyperbilirubinemia in term and late preterm infants

Ronald J Wong, BA
Vinod K Bhutani, MD, FAAP
Section Editor
Steven A Abrams, MD
Deputy Editor
Melanie S Kim, MD


Almost all newborn infants develop a total serum or plasma bilirubin (TB) level greater than 1 mg/dL (17.1 micromol/L), which is the upper limit of normal for adults. As TB increases, it produces neonatal jaundice, the yellowish discoloration of the skin and/or conjunctiva (as visualized on the sclerae) caused by bilirubin deposition [1]. Neonates with severe hyperbilirubinemia (defined as a TB >25 mg/dL [428 micromol/L]) are at risk for bilirubin-induced neurologic dysfunction (BIND), which occurs when bilirubin crosses the blood-brain barrier and binds to brain tissue (figure 1). As a result, it is important to identify and manage infants who are at risk for developing hyperbilirubinemia. (See "Clinical manifestations of unconjugated hyperbilirubinemia in term and late preterm infants", section on 'Neurologic manifestations'.)

The evaluation of neonatal unconjugated hyperbilirubinemia, including identifying at-risk infants is reviewed here. The pathogenesis, etiology, clinical manifestations, prevention, and treatment of hyperbilirubinemia are discussed separately. (See "Pathogenesis and etiology of unconjugated hyperbilirubinemia in the newborn" and "Clinical manifestations of unconjugated hyperbilirubinemia in term and late preterm infants" and "Treatment of unconjugated hyperbilirubinemia in term and late preterm infants".)


Neonatal hyperbilirubinemia in infants ≥35 weeks gestational age (GA) is defined as total serum or plasma bilirubin (TB) >95th percentile on the hour-specific Bhutani nomogram (figure 1) [2].

Severe neonatal hyperbilirubinemia is defined as a TB >25 mg/dL (428 micromol/L). It is associated with an increased risk for bilirubin-induced neurologic dysfunction (BIND), which occurs when bilirubin crosses the blood-brain barrier and binds to brain tissue. (See "Clinical manifestations of unconjugated hyperbilirubinemia in term and late preterm infants", section on 'Neurologic manifestations'.)

Acute bilirubin encephalopathy (ABE) is used to describe the acute manifestations of BIND. (See "Clinical manifestations of unconjugated hyperbilirubinemia in term and late preterm infants", section on 'Acute bilirubin encephalopathy'.)


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Literature review current through: May 2017. | This topic last updated: Jun 06, 2017.
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