What is Neonatal Hyperbilirubinemia?

Neonatal hyperbilirubinemia, or neonatal jaundice, is a condition in which the eyes and skin of newborn babies develop a yellow hue. This is caused by high blood levels of a substance known as bilirubin. Bilirubin is mostly formed when red blood cells are broken down, and it is normally carried to the liver, where it is processed and added to bile, the digestive fluid inside the gallbladder. Neonatal hyperbilirubinemia is common, and usually harmless, in the first few days of life, due to a newborn's liver not being fully developed at a time when there is a rise in the number of red blood cells being broken down. Occasionally, jaundice can also be a sign of diseases such as hypothyroidism, infections and some anemias.

Symptoms of neonatal hyperbilirubinemia typically appear on day two or three after birth. If jaundice develops earlier or later than that, it suggests that there may be an underlying illness. Yellow coloring first appears on the face, before spreading to the torso and, finally, the limbs. Most often there are no other unusual findings, other than sleepiness if the jaundice is very pronounced.

Signs such as seizures are important because they could indicate the onset of a life-threatening condition known as kernicterus. Kernicterus mostly affects babies born prematurely and is the result of bilirubin entering the brain where it causes brain damage. It can be prevented by treatment to correct high levels of bilirubin in the blood.

Treating neonatal hyperbilirubinemia first involves attending to any underlying cause. Some causes of neonatal hyperbilirubinemia may require surgery, such as biliary atresia, where the bile ducts are blocked and bile builds up, damaging the liver. In other cases, such as hemolytic anemia, where the breakdown of red cells is greatly increased, an exchange transfusion may be needed. During an exchange transfusion, small samples of blood are removed and replaced with blood from a donor. This technique can be used to rapidly lower bilirubin levels.

The most commonly used method for treating jaundice in infants is phototherapy. Although individual neonatal health units will use the technique in different ways, phototherapy for jaundice treatment is normally started straight away, if there is thought to be a risk of bilirubin levels rising quickly. The phototherapy method uses light to change bilirubin into a different form, which is more soluble in water and which can be more easily disposed of by the kidneys and liver. For most babies with neonatal hyperbilirubinemia, the outlook is positive, although this will depend upon the underlying cause.