Kernicterus is caused by very high levels of bilirubin. Bilirubin is a yellow pigment that is created in the body during the normal recycling of old red blood cells. High levels of bilirubin in the body can cause the skin to look yellow (which is called jaundice).
In some cases when there are extremely high levels of bilirubin in the body or the baby is extremely ill, the substance will move out of the blood and collect in the brain tissue. This can lead to serious neurological complications, including brain damage and hearing loss.
Kernicterus usually develops in the first week of life, but may be seen up until the third week. Newborns with Rh hemolytic disease that may lead to hydrops fetalis are at high risk for severe jaundice that leads to this condition. However, kernicterus has been seen in apparently healthy babies.
The symptoms depend on the stage of kernicterus.
Absent startle reflex
Poor feeding or sucking
Extreme sleepiness (lethargy)
Arched back with neck hyperextended backwards
Bulging fontanel (soft spot)
Late stage (full neurological syndrome):
High-frequency hearing loss
Signs and tests
A blood test will show a high bilirubin level (greater than 20-25 mg/dL).
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
Treatment depends on how old the baby is (in hours) and whether the baby has any risk factors (such as prematurity). It may include:
Light therapy (phototherapy)
Kernicterus is a serious condition. The outcome is guarded. Many infants with late stage nervous system complications die.
Permanent brain damage
Calling your health care provider
Seek immediate medical help if your baby has signs of this condition.
Early diagnosis and treatment of jaundice or conditions that lead to jaundice may help prevent this complication. The American Academy of Pediatrics recommends that infants with the first signs of jaundice have their bilirubin level measured within 24 hours. If the level is high, the infant should be screened for diseases that involve the destruction of red blood cells (hemolysis).
The association also recommends that all newborns have a follow-up appointment within 2 to 3 days after leaving the hospital. This is particularly important for premature or near-term babies.
American Academy of Pediatrics. Committee on Fetus and Newborn. Hospital stay for healthy term newborns. Pediatrics. 2010; 125: 405.
American Academy of Pediatrics, Subcommittee on Hyperbilirubinemia Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation. Pediatrics. 2004;114: 297-316.
Kimberly G Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.