What is a key characteristic of physiologic jaundice in newborns?

A key characteristic of physiologic jaundice in newborns is that it is caused by an immature liver and normal red blood cell (RBC) breakdown. In neonates, physiological jaundice typically manifests because the newborn's liver is not fully developed, and it may not effectively process bilirubin. This condition occurs in the context of the natural breakdown of RBCs, which is a normal process, particularly after birth when the newborn transitions from intrauterine to extrauterine life.

Physiologic jaundice usually appears after the first 24 hours following birth and tends to resolve within the first two weeks of life. The bilirubin levels in this condition are typically unconjugated, not conjugated, which distinguishes it from pathologic jaundice. Therefore, the characterization of physiologic jaundice hinges on the interplay between the immature liver function and the normal physiological processes of bilirubin production and metabolism.