What is hyperbilirubinemia?

Hyperbilirubinemia is a condition in which there is a build up of bilirubin in the blood, causing yellow discoloration of the eyes and skin, called jaundice. Low levels of bilirubin in the newborn is common and does not cause any trouble and will resolve on its own in the first week of life. However some conditions like prematurity, infection or certain blood disorders can lead to a rapid accumulation of bilirubin to a toxic level.

Depending on the cause of the hyperbilirubinemia, jaundice may appear at birth or at any time afterward.

What causes hyperbilirubinemia?

Bilirubin is a natural byproduct produced when red blood cells breakdown. The adult liver converts unconjugated bilirubin into a conjugated form, that be excreted. During pregnancy, the placenta excretes bilirubin but when the baby is born, the baby's immature liver must assume that role. There are several causes of hyperbilirubinemia and jaundice, including the following:

• Physiologic jaundice. Physiologic jaundice occurs as a "normal" response to the baby's limited ability to excrete bilirubin in the first days of life due to the immaturity of the liver. This will usually resolve by the first week of life.
• Breastfeeding failure jaundice. During the first few days of breastfeeding when the maternal breast milk supply is low and the baby is having trouble latching and feeding, the baby may become dehydrated. Since bilirubin is eliminated in the urine and stool, decreased urination and infrequent stools result in a buildup of bilirubin. While common in full term infants, premature infants and late preterm infants are more susceptible to this problem because they may have uncoordinated suck as well as easy fatigability. Once effective breastfeeding is established, this problem will resolve.
• Breast milk jaundice. About 2 percent of breastfed babies develop jaundice after the first week. It peaks about two weeks of age and can persist up to three to twelve weeks. Breast milk jaundice is thought to be caused by a substance in the breast milk that increases the reabsorption of bilirubin through the intestinal tract. Breastfeeding can usually continue or only be interrupted briefly.
• Jaundice from hemolysis. Jaundice may occur if there is an increase of red blood cell breakdown (hemolysis) such as that seen when there is a mismatch of maternal and fetal blood type, resulting in ABO incompatibility or hemolytic disease of the newborn (Rh disease). Increased hemolysis can also occur if the baby is bruised or develops a hematoma during delivery.
• Jaundice related to inadequate liver function. Jaundice may be related to prolonged liver dysfunction due to infection and other factors.

Who is affected by hyperbilirubinemia?

Hyperbilirubinemia is very common, affecting approximately 60 percent of term newborns and 80 percent of premature babies develop jaundice.

Why is hyperbilirubinemia a concern?

Although low levels of bilirubin are not usually a concern, large amounts can circulate to tissues in the brain and may cause seizures and brain damage. This condition is called kernicterus.

What are the symptoms of hyperbilirubinemia?

Elevated bilirubin is evident by yellow discoloration of the baby's eyes, mucosa and skin, usually starting from the head and moving downward. Prior to discharge in the hospital, most babies will have their bilirubin level checked, either by a skin (transcutaneous) probe or a blood test. Other symptoms of jaundice may include poor feeding or lethargy.

The symptoms of hyperbilirubinemia may resemble other conditions or medical problems. Always consult your baby's primary care provider for a diagnosis.

How is hyperbilirubinemia diagnosed?

The timing of the appearance of jaundice helps with the diagnosis. Jaundice appearing in the first 12-24 hours can be serious and may require early treatment. When jaundice appears on the second or third day, it is usually "physiologic" or related to dehydration. The physician will usually rely on a bilirubin tool or graph to decide when the level of bilirubin becomes dangerous as infants who are a few days old can tolerate higher levels of bilirubin compared to an infant who is less than 48 hours old. When jaundice appears toward the end of the first week, it may be due to an infection. Later appearance of jaundice in the second week, is often related to breast milk feedings, but may have other causes.

Diagnostic procedures for hyperbilirubinemia may include:

• Direct and indirect bilirubin levels. A blood test can determine if the bilirubin is bound with other substances by the liver so that it can be excreted (direct), or is circulating in the blood circulation (indirect).
• Red blood cell count may be used to determine if the baby has too many or too few red blood cells.
• Reticulocyte count determines the number of young red blood cells, which is an indication of red blood cell production.
• Blood type and testing for ABO or Rh incompatibility (Coomb's test)