Neonatal bilirubin is a yellow breakdown product of normal heme catabolism in newborns. Its levels are elevated in certain diseases and responsible for the yellow color of bruises.
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 levels in newborns not get too high. When the level of bilirubin is above a critical threshold, special treatments are initiated to lower it.