KIDS
November 3, 2009

Bilrubin Tests For Newborns

It doesn't happen often, but when a newborn has jaundice and high bilirubin levels that don't gradually recede, there is a chance of kernicterus, a devastating neurobiological disorder...

Many newborns develop jaundice over the first few days of life. For most, this yellowish−tinge to the skin and white of eyes is a benign condition brought on by the presence of bilirubin, the breakdown product of red blood cells. The liver usually breaks the bilirubin down so it can be excreted through the intestine but sometimes there is more produced than the liver can handle and a temporary excess develops, resulting in jaundice. Usually, the jaundice resolves (goes away) with simple measures such as ensuring that the infant is receiving adequate calories and protein in her diet and that she has no signs of illness.

However, if the bilirubin enters into the brain tissue, very high levels of bilirubin in the baby's blood can cause a devastating complication. This condition is called kernicterus and causes significant neurodevelopmental problems. Avoiding kernicterus depends on identifying babies who are risk for unusually high bilirubin levels, and treating them early, before the level gets dangerously high.

Avoiding kernicterus depends on identifying babies who are risk for unusually high bilirubin levels, and treating them early, before the level gets dangerously high.

Often several measurements of an infant's blood bilirubin level are needed to give important information about how high the bilirubin is and whether it is going up or down. Early treatment is done with special lights and is called phototherapy. It is usually done in the hospital, but can be done in the home. In some situations, when the bilirubin reaches dangerous levels, a special type of transfusion is required to help lower the bilirubin to safe levels.

In 2004, the American Academy of Pediatrics developed guidelines aimed at decreasing the incidence of kernicterus by recommending that every baby have a bilirubin measurement and/or be evaluated for her risk of elevated bilirubin before being discharged from the hospital. A study recently published in the October issue of Pediatrics assessed whether this new policy had had the intended outcomes: decreasing the incidence of brain damage caused by very high bilirubin, without increasing anxiety, unnecessary testing, and treatment of babies who were not at high risk.

The researchers compared the records of full term, normal weight infants who were born before and after the AAP recommendation for universal screening. They found that in the group born after the recommendations, there was, as expected, an increase in the number of bilirubin tests performed. And happily, the more infants whose bilirubin levels were measured, the lower the number of cases of dangerously high bilirubin levels. In fact there was a 62% reduction in the numbers of infants whose bilirubin measurements reached 25 or higher, the level considered to potentially cause kernicterus. There was also a 56% increase in the number of infants whose bilirubins were identified to be elevated enough to warrant early light treatment to prevent it from rising further. Though it is impossible to know for sure, this earlier identification and treatment of infants whose bilirubins were rising abnormally, is likely to have prevented some of the babies from reaching 25.

There was an increase in the use of special light therapy (phototherapy) in the hospitals with universal screening, both during the birth hospitalization and upon readmission for treatment of elevated levels found after the baby was discharged. Among these infants, the number who were receiving phototherapy appropriate for their bilirubin measurements increased, but so did the number of infants who were treated for bilirubins that were actually too low to warrant phototherapy, according to the AAP guidelines. This increase in unwarranted phototherapy may have been caused by increased anxiety about bilirubin levels and concern that the level, though not yet abnormal, would continue to increase and the patient would not have adequate follow up once discharged. The researchers noted that although universal screening definitely decreased the numbers of infants whose bilirubin reached a threatening level, there were not enough cases of kernicterus among the study cohort to establish whether screening prevented this dreaded outcome.

New parents should not be surprised if their baby's doctor orders a blood test for bilirubin on their newborn. Nor should they be alarmed if another follow up test is ordered once the baby leaves the hospital. They may want to ask their doctor if she has any specific concerns about their baby's risk for jaundice and if there is anything they should watch for. Parents should be sure to follow up with any blood tests or doctor visits that are recommended when the baby leaves the nursery. And, as always, new parents should contact their baby's doctor if they feel their baby looks or is acting unwell, or is feeding poorly.

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