National Standards Issued for Diagnosing, Treating PKU
Oct. 18, 2000 (Washington) -- Almost 40 years after the U.S. began screening all newborns for phenylketonuria (PKU), a panel of experts has issued the nation's first consensus standards for how to diagnose and treat this metabolic disorder, which, if left untreated, can lead to profound mental retardation.
PKU is a rare, inherited disorder associated with a deficiency of a liver enzyme. This deficiency leads to the accumulation of an amino acid called phenylalanine in the blood and tissues. That can result in brain damage early in childhood that continues into adulthood, usually resulting in mental retardation. Treatment requires avoiding foods with this amino acid, which is a building block of proteins.
The standards released Wednesday were developed by an independent panel of experts assigned by the National Institutes of Health to resolve questions about the diagnosis and treatment of this disorder. Although the research on PKU continues to broaden, its treatment and diagnosis now varies from state to state and physician to physician, due mostly to the lack of clear-cut policies.
For instance, while some states offer follow-up services such as counseling to the families of those with the disorder, others do not offer the social services families may need to address the school, family, and behavioral difficulties that can accompany PKU. And while some doctors recommend ending treatment after childhood, others say it should continue throughout the patient's lifetime.
Among the panel's recommendations were that treatment be lifelong and that pediatricians caring for children with PKU adopt a multidisciplinary approach that includes encouraging family counseling. The panel also recommended that states develop policies to help these families get the medical services they need and to ensure that appropriate screening, treatment, and data collection are taking place.
Despite the panel's efforts to include caveats, such as the need for further research into the causes and mechanisms of PKU, not everyone supports its recommendations.
"You have got to remember that there is such a thing as junk science," says Samuel Bessman, MD, chair of pharmacology and professor of pediatrics at the University of Southern California School of Medicine.
According to Bessman, the panel's recommendations largely ignore the fact that some patients with PKU never develop mental retardation. They also ignore the fact that treatment of PKU can itself have harmful effects, and that the most commonly used diagnostic test for PKU is not 100% accurate, he says.
"My fear is that they are making suggestions based on numbers that are not wholly accurate," he tells WebMD.
The current treatment for PKU involves putting patients on a diet that excludes all high-protein foods, such as milk, eggs, and nuts. The reason is that all protein contains phenylalanine. When a strict diet is begun early and phenylalaline levels are controlled, experts believe that children with PKU can develop normally.