A newborn infant presents with jaundice on day two; which type of bilirubin is most likely elevated and what is management?

• A. Conjugated bilirubin elevation with physiologic jaundice.
• B. Unconjugated bilirubin due to breast milk jaundice.
• C. Physiologic jaundice with unconjugated bilirubin; observation and frequent feeds; phototherapy if high or risk; exchange transfusion if very high.
• D. Conjugated bilirubin elevation requiring immediate phototherapy.

Answer: (C)

Newborn physiologic jaundice is characterized by a rise in unconjugated (indirect) bilirubin due to immature liver metabolism and high bilirubin turnover in the first days of life. The day-two onset fits this pattern, and most term infants have predominantly unconjugated bilirubin that gradually declines as liver conjugation improves.

Management centers on supporting clearance and preventing complications. Adequate feeds and hydration promote regular stooling, which helps excrete bilirubin and reduces enterohepatic circulation. Phototherapy is added if bilirubin levels reach a threshold or if the infant has risk factors, because light converts unconjugated bilirubin into water-soluble isomers that can be excreted without conjugation. Exchange transfusion is reserved for very high unconjugated bilirubin levels or signs of bilirubin-induced neurologic injury, where rapid reduction is needed.

Conjugated bilirubin elevation would suggest a hepatobiliary problem (not typical this early in life), and breast milk jaundice usually appears later, after the first week, so it’s less likely in this scenario.