Kernicterus in newborns is primarily caused by what condition?

Kernicterus is a serious neurological condition that arises due to excessive bilirubin in the blood, commonly associated with severe jaundice in newborns. When the bilirubin levels become critically high, particularly unconjugated bilirubin, it can cross the blood-brain barrier and lead to brain damage, which characterizes kernicterus. The primary risk factor for developing kernicterus is indeed excessive jaundice resulting from conditions such as hemolytic disease of the newborn, where there is increased breakdown of red blood cells.

Other conditions such as congenital heart defects, respiratory distress syndrome, and hypoglycemia are significant neonatal issues but do not directly lead to kernicterus. While these conditions can result in stress or other metabolic issues in the newborn, they do not involve the excessive accumulation of bilirubin that is crucial for the development of kernicterus. Thus, excessive jaundice is recognized as the leading cause of this serious condition.