Department of Family Medicine, Naval Hospital Camp Pendleton, Calif (Dr. Pace); Department of Family Medicine, University of Virginia, Charlottesville (Drs. Brown and DeGeorge) kd6fp@virginia.edu
The authors reported no potential conflict of interest relevant to this article.
The views expressed in this publication are those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the US government.
This review provides the latest advice on the screening and management of hyperbilirubinemia in term infants.
More than 60% of newborns appear clinically jaundiced in the first few weeks of life,1 most often due to physiologic jaundice. Mild hyperbilirubinemia peaks at Days 3 to 5 and returns to normal in the following weeks.1 However, approximately 10% of term and 25% of late preterm infants will undergo phototherapy for hyperbilirubinemia in an effort to prevent acute bilirubin encephalopathy (ABE) and kernicterus.2
Heightened vigilance to prevent these rare but devastating outcomes has made hyperbilirubinemia the most common cause of hospital readmission in infants in the United States3 and one with significant health care costs. This article summarizes the evidence and recommendations for the screening, evaluation, and management of hyperbilirubinemia in term infants.
But first, we begin with a quick look at the causes of hyperbilirubinemia.
Causes of conjugated vs unconjugated hyperbilirubinemia
Bilirubin is generated when red blood cells break down and release heme, which is metabolized into biliverdin and then to bilirubin. Unconjugated bilirubin binds to albumin in the blood and is transported to hepatocytes where conjugation occurs, allowing it to be excreted through the gastrointestinal tract. In neonates, most of the conjugated bilirubin that reaches the gut is then unconjugated, resulting in its recirculation. Additionally, neonates have an increased volume of red blood cells and a slow conjugating system. These factors all contribute to excess unconjugated bilirubin, which manifests as physiologic, nonpathologic jaundice.4TABLE 14-6 lists causes of unconjugated hyperbilirubinemia.
Elevated conjugated hyperbilirubinemia(conjugated bilirubin level ≥20% of total serum bilirubin [TSB]) is always pathologic and occurs due to intrahepatic or extrahepatic obstruction. TABLE 27 lists causes of conjugated hyperbilirubinemia. Infants found to have conjugated hyperbilirubinemia should undergo an additional work-up to determine the cause and identify potential complications of this disease.8
Given that the differential for conjugated hyperbilirubinemia is so broad and that it is often associated with severe disease requiring complicated and invasive treatments, infants with conjugated hyperbilirubinemia should be referred to a pediatric tertiary care facility with pediatric gastroenterologists, infectious disease specialists, and surgeons.7
What puts newborns at risk?
Major and minor risk factors for the development of severe hyperbilirubinemia in well newborns ≥35 weeks’ gestation are listed in TABLE 3.9 Those that carry the highest risk include gestational age <38 weeks, having a sibling who required phototherapy, visible jaundice by the time of discharge, and exclusive breastfeeding.9 Several more recent cohort studies, however, suggest that breastfeeding may not be a significant risk factor.10 The more risk factors present, the higher the risk. Infants who are formula fed, age ≥41 gestational weeks, or have no major or minor risk factors have a very low likelihood of developing severe hyperbilirubinemia.9