Bilirubin

When bilirubin levels are high, a condition called jaundice occurs, and further testing is needed to determine the cause. It is not uncommon to see high bilirubin levels in newborns, typically 1 to 3 days old. This is sometimes called physiologic jaundice of the newborn.
Newborns: Excessive bilirubin damages developing brain cells in infants (kernicterus) and may cause mental retardation, learning and developmental disabilities, hearing loss, or eye movement problems. It is important that bilirubin in newborns does not get too high. When the level of bilirubin is above a critical threshold, special treatments are initiated to lower it. An excessive bilirubin level may result from the accelerated breakdown of red blood cells due to a blood type incompatibility between the mother and her newborn (e.g., the mother is Rh-negative and has antibody to Rh-positive blood - the father is Rh-positive, and the fetus inherits this trait from him; the mother’s antibody crosses the placenta and causes the fetal Rh-positive red blood cells to hemolyze, resulting in excessively elevated bilirubin levels with jaundice, anemia, and possible kernicterus.)