Abstract and Introduction
Metabolic disorders are individually rare, but when considered together as a disease entity are relatively frequent, occurring in 1 in 1000 to 1 in 3000 infants. Some disorders can have devastating and irreversible outcomes if not diagnosed early and treated promptly. Newborn screening is a vital step in identifying infants with inborn metabolic disorders, hemoglobinopathies, infectious processes, and congenital endocrinopathies; the goal is early recognition and treatment. This article summarizes the critical aspects of newborn screening, comparing and contrasting current national screening practices, and identifying key considerations for clinical care, parental education, and support. To prevent morbidity and mortality, healthcare providers must understand the purpose and guidelines for newborn screening. Providers are also responsible for informing parents about the implications of newborn screening to improve awareness and understanding.
Every year, 4 million infants born in the United States are routinely screened for inborn disorders, and more than 3000 infants are diagnosed with severe disorders. This is accomplished by individual state newborn screening programs. Newborn screening programs often provide services beyond the early screening tests; they also provide follow-up testing of screen-positive infants, confirmation and diagnosis, short- and long-term treatment, education, and evaluation of the process.[2,3]
Newborn screening was one of the first and largest population-based disease intervention programs in the United States.[2,4] Statewide programs were initially designed to detect infants with possible inborn errors of metabolism (IBEM), which are genetically determined and typically inherited in an autosomal recessive pattern.[5,6] Many states have since expanded their programs to include other nonmetabolic disorders, such as hematological disorders and endocrinopathies. If screening is positive or results are unusual, additional testing is performed to confirm the diagnosis. After the diagnosis is confirmed, medical interventions, usually consisting of special diets, vitamins, or pharmacological treatment, are initiated. Infants and children are then followed over time to confirm effectiveness of treatment. Comprehensive lifelong services are essential to those infants with chronic disease and their families.[2,7]
The goal of newborn screening programs is to detect diseases early, preferably before the onset of symptoms, so timely treatment can be initiated. Early detection of these disorders before irreversible organ damage occurs may lead to more effective treatment and more favorable outcomes. If the disease is undiagnosed and untreated, or if treatment is delayed for even a brief period of time, the infant may suffer from irreversible damage. For example, there is an inverse relationship between the age at the start of treatment and intelligence quotient in infants diagnosed with congenital hypothyroidism.
Untreated metabolic disorders may result in liver disease, physical disability, mental retardation, and even sudden death. Early clinical signs of metabolic disorders are nonspecific and difficult to distinguish in infants. Some disorders are asymptomatic in the neonatal period and present later in life. Metabolic disease mimics many other conditions; often the healthcare provider may not immediately identify IBEM as the underlying etiology. Testing may also be delayed because IBEM are perceived as rare disorders. The infant may be lethargic, jaundiced with or without hepatosplenomegaly, demonstrate poor feeding behavior, and/or may fail to thrive. In some disorders, such as hyperphenylalaninemia, there are no early symptoms at all.
Healthcare providers are responsible for understanding the screening tests available in their state and the requirements for testing. They must understand the guidelines for the screening tests so that morbidity and mortality may be prevented.
Adv Neonatal Care. 2004;4(5) © 2004 W.B. Saunders
Cite this: A Primer on Newborn Screening - Medscape - Oct 01, 2004.