Bilirubin Levels and Jaundice

When bilirubin levels become dangerous

Baby under lights in hospital
Jennifer Polixenni Brankin/Contributor/Getty Images

Bilirubin is a yellowish pigment formed in the liver by the breakdown of red blood cells and excreted in bile. High levels of bilirubin can lead to jaundice or yellowing of the skin and eyes. Jaundice is a common condition that affects newborns because all newborn babies go through a period of rapid red blood cell breakdown after birth.

Jaundice is typically mild, goes away on its own and leaves no lasting effects, but some babies get severe jaundice, also known as hyperbilirubinemia.

There are several things that increase the risk of developing hyperbilirubinemia:

  • Premature birth
  • A blood group incompatibility with the mother
  • Not feeding well
  • Significant bruising at birth
  • Jaundice appeared within the first 24 hours of life 

Blood tests are used to measure bilirubin levels in the blood. When a baby's bilirubin levels start to climb, special phototherapy lights are used to remove the yellowish pigment from the skin.

What Bilirubin Levels Aren't Normal

Some bilirubin in the blood is normal. But what is "normal" varies because different labs use different measuring techniques or test different samples. Normal ranges of bilirubin are as follows:

  • Direct bilirubin: 0 to 0.3 mg/dL
  • Total bilirubin: 0.3 to 1.9 mg/dL

For newborns, bilirubin levels are higher during the first few days of life. Doctors evaluate a baby's bilirubin levels based on the baby's risk for severe jaundice and age in hours.

For a baby with no risk factors, doctors may start to worry about severe jaundice if the level is:

  • 24 hours old: 8 mg/dL
  • 48 hours old: 13 mg/dL
  • 72 hours old: 16 mg/dL
  • 96 hours old: 17 mg/dL

If a baby's bilirubin gets this high, doctors will monitor the baby closely and make sure it begins to decline. Doctors also have to consider how rapidly the level has been rising, whether the baby was born preterm and the baby's age.

For more details, please use the American Academy of Pediatrics BiliTool.

The Risks of High Bilirubin Levels

Bilirubin levels that are too high can cause serious illness. A baby usually appears tired and is difficult to feel. Their skin and eyes can take on a yellow hue. If left untreated, jaundice can lead to kernicterus, a type of permanent brain damage. For healthy, full-term babies, kernicterus rarely occurs at bilirubin levels less than about 35 mg/dL. For premature babies, kernicterus can occur at lower levels. It is still rare at levels less than 20 mg/dL.

Because jaundice is easy to test and to treat, kernicterus is very rare in the modern world. By following up with your baby's pediatrician after your take your baby home from the hospital, you can make sure that your baby stays safe and healthy.

Other Causes of Jaundice

Jaundice is caused by the breakdown of red blood cells after birth. In some cases, jaundice can be attributed to certain conditions that cause red blood cells to break down. These conditions include:

  • Erythroblastosis fetalis (a blood disorder)
  • Hemolytic anemia (a red blood cell disorder)
  • Transfusion reaction (red blood cells given via transfusion are destroyed by the immune system)

    See Also


    American Academy of Pediatrics Subcommittee on Hyperbilirubinemia. "Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation." Pediatrics. July 2004; 114, 297-323.

    Ebbesen F, Bjerre JV, Vandborg PK. "Relation Between Serum Bilirubin Levels ≥450 μmol/L and Bilirubin Encephalopathy; a Danish Population-Based Study." Acta Paediatr. April 2012; 101, 384-9.

    Okumura, A., Kidokoro, H., Shoji, H., Nakazawa, T., Mimaki, M., Fujii, K., Oba, H., & Shimizu, T. "Kernicterus in Preterm Infants." Pediatrics June 2009; 123, e1052-e1058.

    U.S. National Library of Medicine. Bilirubin blood test. (2015, February 8).