Increase in mandatory Screening Test for Newborns May Pose Risks

More tests may mean more false-positive results. All states require some degree of screening tests for newborns, from more than 40 tests to fewer than five. In Washington state, the law requires all newborns be tested for 10 disorders.

More tests may mean more false-positive results. All states require some degree of screening tests for newborns, from more than 40 tests to fewer than five. In Washington state, the law requires all newborns be tested for 10 disorders.

The advent of tandem mass spectrometry equipment has made it possible to test newborns for multiple conditions, simultaneously, with a single drop of blood. The blood is collected through a heel prick to the infant before they leave the hospital, or within one week of being born at home.

In Washington state, several drops of blood are collected on a filter paper cards, dried and sent for testing to the Washington State Newborn Screening Laboratory, which is run by the Washington State Department of Health, in Shoreline, WA.

The newborn screening tests are conducted and interpreted by a team of laboratory scientists using technology called tandem mass spectrometry.

But the increase in the number of required newborn screening tests may result in an unintended consequence — an increase in false positive results in the tests, according to a study published in the August issue of Pediatrics, the official journal of the American Academy of Pediatrics.

The study’s principal investigator is Beth A. Tarini, MD, Robert Wood Johnson Clinic Scholars Program and professor in the Department of Pediatrics at the University of Washington. Dr. Tarini is also a pediatrician at Children’s Hospital and Regional Medical Center in Seattle.

“Newborn screening is important, because it allows us to identify rare, but serious disorders in infants, so that they can be treated early. However, we need to be cautious in adding more mandated tests to the list.” said Dr.Tarini.

“Our research found that the number of false positive results go up with an increase in the number of disorders screened using tandem mass spectrometry. In other words, the greater the number of tests run on a single drop of blood, the greater the likelihood of a false positive result. We don’t want a child to be falsely labeled as having a disease or disorder.”

The researchers obtained data from the National Newborn Screening and Genetics Resource Center regarding the screening practices for each of the 50 states to determine the number of mandated disorders added to state newborn screening panels over a 10 year period (1995-2005).

They then looked at the rate of false positive results in each state as compared to the number of tests required and the number of births. They found a correlation between the number of test conducted using tandem mass spectrometry and the rate of false positive results.

In Washington state, the number of tests increased from four in 1995 to nine in 2005. Since then, the state has added one additional test to the panel, bringing the total number to 10 tests mandated in the state.

In Washington state, newborns are tested for the following disorders:

  1. Phenylketonuria (fen-ill-key-toe-new-re-uh) (PKU)
  2. Congenital Hypothyroidism (hi-po-thigh-roid-is-um)
  3. Congenital Adrenal Hyperplasia (hi-purr-play-she-uh) (CAH)
  4. Cystic Fibrosis
  5. Hemoglobinopathies
  6. Biotinidase Deficiency
  7. Galactosemia
  8. Homocystinuria
  9. Maple Syrup Urine Disease (MSUD)
  10. Medium-Chain Acyl co-A Dehydrogenase (MCAD) Deficiency

A new report from the American College of Medical Genetics (ACMG), recommend that infants receive a total of 29 tests at birth — a hearing test and 28 tests for rare but serious disorders, using a blood specimen. The American Academy of Pediatrics (AAP) supports the ACMG report.

In each state, legislators and Health Boards review and decide which newborn screening tests will be mandated for infants in each state. Washington state policy makers are reviewing the ACMG report and will make recommendations to the State Legislature about whether to add additional tests to the newborn screening panel.

Parents and caregivers who have questions about newborn screening, should talk with their child’s pediatrician, family practice doctor or health care provider about what tests are required and what additional tests may be warranted.

Additional newborn screening tests are available through private laboratories.

About Seattle Children’s

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