How Helpful Is Expanded Newborn Screening?
New Screening Method Is Good, but Parents Need More Information
Nov. 18, 2003 -- It's every parent's nightmare: His or her baby is slow to develop or dies suddenly, the victim of a rare genetic disorder that could have been treated -- if it were only detected and treated early.
Since the 1960s, the PKU screening test has been performed in every state to detect one such condition -- phenylketonuria, a rare inherited condition that can cause mental retardation and neurological problems if treatment is not started within the first days of life. Most states also require testing for congenital hypothyroidism. A handful of other diseases have been added over the years on a state-by-state basis. But in recent years, a newer expanded newborn screening procedure has been available -- tandem mass spectrometry can detect at least 20 metabolic disorders in a single evaluation.
One Procedure, 20 Tests
Instead of testing for individual disorders with specific tests, this procedure can screen for a host of conditions from a few drops of blood taken from the newborn's heel typically within 48 hours of birth. The blood is examined for the presence of high levels of certain fatty acids, amino acids, or other chemicals that could signal a genetic defect in how their body processes them.
But while tandem mass spectrometry -- now done in 24 states, sometimes by mandate -- can identify an otherwise undetected rare disease, there are concerns over making this a standard in newborn screening.
This one test can identify numerous genetic conditions but its start-up costs are steep -- typically about $400,000 for the necessary equipment. And there are concerns that these tests might lead to unnecessary parental stress and hurried, uneducated, and fragmented decision-making.
A study in this week's Journal of the American Medical Association addresses some of those concerns. Researchers say tandem mass spectrometry offers many benefits, along with some drawbacks, compared with having newborns evaluated through a medical exam alone.
"Our data suggests that expanded newborn screening prevents the most severe consequences of these biochemical genetic disorders -- it works," says lead researcher Susan E. Waisbren, PhD, of Children's Hospital Boston and Harvard Medical School. "
Children identified with genetic disorders by newborn screening may experience fewer developmental and health problems, and they function significantly better in diverse areas of daily living, write the researchers. "It's a huge benefit," she tells WebMD.
False Positives Create True Problems
But her study finds that false-positive results understandably cause parents a great deal of stress. "We have to recognize that false-positive results can be extremely stressful unless the test and conditions are fully explained to the family by an expert," Waisbren tells WebMD.
"Sometimes, parents are just told, 'No news is good news,' or not told anything. Those parents are much more stressed than those who get the news through a face-to-face conversation with their doctor or another expert, especially when there's a positive finding -- whether it's correct or a false positive."