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Kernicterus refers to brain damage that occurs due to high levels of bilirubin in the blood. Bilirubin is a waste product produced by your liver after the breakdown of red blood cells. In most newborn babies, bilirubin levels are usually high, resulting in newborn jaundice. Kernicterus, on the other hand, is a serious condition because, in this case, the bilirubin levels are high enough to cause brain damage. If hyperbilirubinemia (a high level of bilirubin) is noticed in a newborn baby, it is monitored closely to prevent its progression to kernicterus. 


Newborn babies have a higher level of bilirubin in their blood. This occurs because, after birth, fetal blood cells are broken down to replace with adult human blood cells. This rapid breakdown exerts stress on the newborn’s liver, which is unable to function efficiently in the initial stages. In a normal person, the liver releases unconjugated bilirubin, which is later converted to conjugated bilirubin and removed from the body. However, in babies, the level of unconjugated bilirubin increases, and it crosses the blood-brain barrier. This can lead to brain damage and neurological issues.


Medical conditions that can lead to the production of high bilirubin include premature birth, Rh incompatibility, Crigler–Najjar syndrome, G6PD deficiency, and polycythemia. Some medications have also been linked with the development of this condition. This can include aspirin and sulfonamides. These medications result in an increase of unconjugated bilirubin in the blood, hence leading to kernicterus. 


Kernicterus is divided into three types based on its duration and severity.

Acute bilirubin encephalopathy comprises an acute state of increased bilirubin levels in the body. This can easily cross the blood-brain barrier and cause multiple neurological dysfunctions, including hypotonia or hypertonia, lethargy, fever, seizures, etc. Death can result in severe cases.

 Subtle bilirubin encephalopathy presents with neurological disorders without the typical findings of kernicterus. It may include hypotonia, ataxia, aphasia, problems with sensory and motor functions, etc.


Chronic bilirubin encephalopathy develops as a consequence of long-term acute bilirubin encephalopathy. The clinical manifestation of this condition usually occurs after one year of age, including abnormal motor functions, disturbance in hearing, oculomotor impairment, and dental enamel hypoplasia. The digestive function may also be impaired.

Risk Factors And Epidemiology

Certain causes of this condition are linked with genetics. If you have a positive family history of medical disorders such as G6PD deficiency, the risk of hyperbilirubinemia is higher in your newborn baby. It also depends on the blood compatibility between baby and mother. Premature birth is another important risk factor. Babies born before 37 weeks of pregnancy have a less efficient liver, leading to further complications.


Kernicterus can develop in any baby due to an underlying cause. It does not have a racial preference. However, kernicterus has been seen to be more common among male newborns than females. 

Signs And Symptoms

The signs and symptoms of kernicterus can vary depending on its type. In the initial stage, jaundice will be present, which is present in most babies. Jaundice can cause yellowish discoloration of the eyes and skin. In babies with kernicterus, the symptoms worsen as the brain damage progresses. These include high-pitched crying, lethargy, fever, loss of appetite, decreased muscle tone, missing reflexes, impaired hearing, impaired eye movements, arching of head and heels, vomiting, twitching of muscles, and seizures. Development of any of these symptoms indicates a medical emergency and should be treated immediately. 


Diagnosis of kernicterus requires history and a physical examination. Your doctor may ask questions about a genetic condition running in the family. Physical examination is done to look for signs of kernicterus such as changes in muscle tone, missing reflexes, jaundice, etc. Transcutaneous bilirubin measurement can be done using a light meter to gauge the amount of bilirubin. If the levels are high, a bilirubin blood test is done to measure the amount of total and direct bilirubin. Other tests may include the blood type of mother and infant, Coomb test, and reticulocyte count. 

Differential Diagnosis

Kernicterus needs to be differentiated from other conditions that may cause neurological symptoms in newborns. These can include head trauma, cerebral palsy, neonatal sepsis, fetal alcohol syndrome, hypoxic-ischemic brain injury, and cretinism. 


The main goal of treatment is to reduce the level of unconjugated bilirubin in the blood. One method to do that is known as phototherapy or light therapy. In this case, the newborn baby is placed under a special light, increasing the breakdown of unconjugated bilirubin. Another method is to transfuse the baby’s blood with a donor’s blood, a little at a time. It is known as exchange transfusion therapy. This decreases the level of unconjugated bilirubin in the body. Increasing the feeding can also help because it helps remove bilirubin through stool. This may be difficult in babies who have lost their appetite. If a baby has developed kernicterus due to blood incompatibility with the mother, intravenous immunoglobulins can be given to eliminate the antibodies against the baby’s blood cells.


No medications are effective in reducing the damage caused by kernicterus. Medications should only be given to a baby if prescribed by a healthcare expert. Aspirin and other antibiotics should not be given to a baby without a doctor’s consent as they can extend the damage. 


The prognosis of kernicterus depends on the severity of the condition and the time of intervention. If the symptoms are diagnosed early, and appropriate treatment is given, it is possible to avoid any brain damage and lead to full recovery. However, if brain damage has already occurred, it cannot be reversed with treatment. Late diagnosis can lead to severe neurological disorders and other complications that can be fatal. 


It is important to monitor the serum bilirubin levels of a newborn baby, especially in the first 24 hours. Premature babies need to be monitored even more closely because they have a higher risk. If symptoms of jaundice appear, it is treated early by light therapy or exchange transfusion therapy in severe cases. Managing the levels of bilirubin in the early stages can prevent the development of kernicterus.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on April 30, 2023.




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