Your Baby’s Screening False Positives
Newborn screening is not the same as diagnostic testing. A diagnostic test can tell with more certainty whether or not a child has a genetic condition. On the other hand, a screening test simply indicates that a child may have a condition. The purpose of a screening test is to catch all babies that may have a condition. This means that many children with an out-of-range screening result are healthy. When a child with an out-of-range newborn screening result has a follow-up test result within the normal range, it is sometimes called a “false positive”.
If your health care provider tells you that confirmation testing shows a false positive result, your child does not have the condition that was suggested by newborn screening. Since genetic conditions are present from birth, the child will not develop this condition in the future. No further follow up testing or treatments are needed, but if you continue to have concerns, tell a health care provider.
A false positive result can occur for many reasons. Newborn screening evaluates the levels of different substances in a baby’s blood. Anything that can cause the levels to be higher or lower than expected can lead to a false positive result. For example, a healthy baby may have an out-of-range newborn screening result if he or she has not eaten enough before the screen, the specimen has been exposed to heat, the initial blood sample was too small, or the test was performed too early. Sometimes a screen comes back positive for a specific condition that the baby ends up not having, but allows the baby’s doctor to see if there is another medical issue. Again, screening is meant to find babies that may be sick early in their lives.