Neonatal Jaundice Physiologic  -  Clinical
Physiologic jaundice Clinical		Normal newborns regularly develop elevated unconjugated bilirubin levels in the first 1-2 weeks of life. This so-called physiologic jaundice results from presentation of an increased bilirubin load to an immature liver (decreased BUG-T activity). The increased load is due to increased bilirubin production, primarily in the first week, and increased enterohepatic recirculation after the first week. As seen in the graph, these levels peak at day 3-5 with a bilirubin that rarely exceeds 12 mg/dL. Then there is a sustained fall until 7-10 days of age when the level reaches the normal value of 1.5 mg/dL. Although this typical pattern is called physiologic jaundice, this term is somewhat of a misnomer. Visible jaundice is not seen in newborns until the bilirubin reaches at least 5-6 mg/dL, while hyperbilirubinemia is defined as a bilirubin > 1.5 mg/dL. Therefore all newborns have physiologic hyperbilirubinemia, but not all are visibly jaundiced. In those patients who do develop jaundice, there is a characteristic spread with the jaundice starting on the face and progressing caudally. It has been written that jaundice confined to the face and head correlates with a serum bilirubin of about 8 mg/dL, jaundice to the chest with a bilirubin to 12, umbilicus to knees 15 and knees to feet 16-18. However, these levels are extremely imprecise and should not be used in lieu of serum bilirubin measurements. Return to top of page