Neonatal jaundice occurs when total serum bilirubin is in excess of 5 mg/dL and progresses in a head-to-toe fashion as levels increase. Most cases of physiologic (< 12 mg/dL) jaundice are self-limited without sequelae and appear on the 2nd or 3rd day of life, peaking between the 3rd and 5th day. Visual estimation of serum bilirubin level is not accurate enough to determine jaundice severity. Preterm infants may peak later.
Neonatal jaundice is due to increased production, deceased clearance, and increased circulation of bilirubin. The increased bilirubin production is a result of turnover of fetal red blood cells, a temporary decrease in conjugation and clearance by the immature newborn liver, and increased enterohepatic circulation. Risk factors for unconjugated (indirect) hyperbilirubinemia include maternal diabetes, prematurity, drugs, polycythemia, traumatic delivery with cutaneous bruising or hematoma, breastfeeding, and ABO (O mother and A/B infant) or Rh(D) incompatibility [Rh(D)-negative mother and Rh(D)-positive infant]. Most infants with jaundice have no “disease” per se, but a careful history and organized approach is necessary to identify potentially pathologic causes. Kernicterus manifests in irreversible neurologic abnormalities and is the long-term result of bilirubin-induced neurologic dysfunction secondary to extreme unconjugated hyperbilirubinemia, which leads to neuronal death and pigment deposition in the basal ganglia and cerebellum.
Management and Disposition
The well-appearing jaundiced infant in day 2 or 3 of life should have a total serum bilirubin level or direct and indirect bilirubin levels sent. Additional labs for the severely jaundiced infant include blood type, Coombs test, complete blood count (CBC) with smear for red cell morphology, reticulocyte count, and indirect and direct bilirubin levels. Transcutaneous bilirubin measurement devices can underestimate total bilirubin at levels > 15 mg/dL; therefore, a serum measurement is recommended for severely jaundiced newborns. Initial management should ensure adequate hydration and phototherapy if the bilirubin level is > 95th percentile. The level of serum bilirubin at which to start phototherapy can be obtained from a standardized nomogram and is dependent upon the infant’s postnatal age in hours, gestational age, and an assessment of risk factors. The goal of phototherapy is to maintain the bilirubin level below 20 mg/dL. Exchange transfusion is considered if the serum level remains elevated (22-25 mg/dL) despite appropriate phototherapy.
Onset of clinical jaundice in the first 24 hours of life strongly suggests the presence of a pathologic process.
Direct serum bilirubin concentration exceeding 10% of total serum bilirubin or 2 mg/dL suggests hepatobiliary disease, a metabolic disorder, or sepsis.
The Bhutani nomogram stratifies the risk of subsequent bilirubin levels being elevated without intervention, not the risk of clinically significant complications and outcomes of hyperbilirubinemia at the specified level.
Neonatal Jaundice. Newborn with yellowish hue to skin consistent with jaundice. (Photo contributor: Kevin J. Knoop, MD, MS.)