Newborn screening tests
Definition
Newborn screening tests look for serious developmental, genetic, and metabolic disorders so that important action can be taken during the critical time before symptoms develop.
In the United States, the individual states each regulate newborn screening, so the diseases screened for vary considerably. Most states require three to eight tests, but organizations such as the March of Dimes and the American College of Medical Genetics suggest more than two dozen additional tests.
The most thorough screening panel checks for about 40 disorders. All 50 states screen for congenital hypothyroidism, galactosemia, and phenylketonuria (PKU).
Alternative Names
Infant screening tests; Neonatal screening tests
How the Test is Performed
Blood tests: A health care professional will prick the babys heel to obtain a few drops of blood. The blood is sent to a lab for analysis.
Hearing test: An audiologist will place a tiny earpiece or microphone in the infants ear or stick electrodes on the babys head.
How to Prepare for the Test
There is no preparation necessary for newborn screening tests. The tests are performed when the baby is between 24 hours and 7 days old, typically before the baby goes home from the hospital.
How the Test Will Feel
The baby will most likely cry when his or her heel is pricked to obtain the small blood sample. The hearing test should not cause the baby to feel pain, cry, or respond.
Why the Test is Performed
Screening tests do not diagnose illnesses. They identify which babies need additional testing to confirm or rule out illnesses. Good screening tests have a low false-negative rate (if the test is normal, the child should be healthy), but may have a high false-positive rate (as many affected children as possible should test positive, even if this means many healthy children also test positive).
If a disorder is diagnosed on follow-up testing, appropriate treatment can be started right away, before symptoms appear.
Screening tests are used to detect a number of disorders, including:
- Amino acid metabolism disorders:
- Arginosuccinic acidemia
- Citrullinemia
- Homocystinuria
- Maple syrup urine disease
- Phenylketonuria (PKU)
- Tyrosinemia type I
- Biotinidase deficiency
- Congenital adrenal hyperplasia
- Congenital hypothyroidism
- Cystic fibrosis
- Fatty acid metabolism disorders:
- Carnitine uptake deficiency
- Long-chain L-3-hydroxyacyl-CoA dehydrogenase deficiency
- Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency
- Trifunctional protein deficiency
- Very long-chain acyl-CoA dehydrogenase deficiency (VLCAD)
- Galactosemia
- Glucose-6-phosphate dehydrogenase deficiency (G6PD)
- Hearing problems
- Human immunodeficiency disease (HIV)
- Organic acid metabolism disorders:
- 3-Hydroxy-3-methylglutaric aciduria (HMG)
- 3-Methylcrotonyl-CoA carboxylase deficiency (3MCC)
- Beta ketothiolase deficiency
- Glutaric acidemia type I
- Isovaleric acidemia
- Methylmalonic acidemia
- Multiple carboxylase deficiency (MCD)
- Propionic acidemia
- Sickle cell disease and other hemoglobinopathy disorders and traits
- Toxoplasmosis
See also: APGAR test
Normal Results
Normal values for each screening test may vary depending on how the test is performed.
What Abnormal Results Mean
An abnormal result means that the child should have additional testing to confirm or rule out the condition.
Risks
Risks for the newborn heel prick blood sample include pain and possible bruising at the site where the blood was obtained.
Considerations
Newborn testing is critical for the baby to receive treatment that may be life saving. However, not all disorders that can be detected by the screening tests can be treated.
Althoughstates do not perform allscreening tests, parents can have additional tests done by qualified laboratories at large medical centers. Private laboratories also offer newborn screening. Parents can find out about extra newborn screening tests from their physician or hospital where the baby will be born, as well as through organizations like the March of Dimes.
References
American College of Medical Genetics Newborn Screening Expert Group. Newborn screening: toward a uniform screening panel and system--executive summary. Pediatrics. 2006 May;117(5 Pt 2):S296-307.
Graves JC, Miller KE, Sellers AD. Maternal serum triple analyte screening in pregnancy. Am Fam Physician. 2002 Mar 1;65(5):915-20.
Grosse SD, Boyle CA, Cordero JF. Newborn screening for cystic fibrosis: recommendations from the Centers for Disease Control and Prevention. Am Fam Physician. 2005 Apr 15;71(8):1482, 1487.
Bryant KG, Horns KM, Longo N, Schiefelbein J. A primer on newborn screening. Adv Neonatal Care. 2004 Oct;4(5):306-17.
Carreiro-Lewandowski E. Newborn screening: an overview. Clin Lab Sci. 2002 Fall;15(4):229-38.
Centers for Disease Control and Prevention. Newborn Screening for Cystic Fibrosis: Evaluation of Benefits and Risks and Recommendations for State Newborn Screening Programs. J Pediatr. 2005 Sep;147(3 Suppl):S1.
Grosse SD, Boyle CA, Botkin JR, et al. Newborn screening for cystic fibrosis: evaluation of benefits and risks and recommendations for state newborn screening programs. MMWR Recomm Rep. 2004 Oct 15;53(RR-13):1-36.
Reviewed By: Alan Greene, M.D., F.A.A.P., Department of Pediatrics, Stanford School of Medicine; Lucile Packard Children's Hospital; Chief Medical Officer, A.D.A.M., Inc., and Deirdre OReilly, M.D., M.P.H., Neonatologist, Division of Newborn Medicine, Childrens Hospital Boston and Instructor in Pediatrics, Harvard Medical School, Boston, Massachusetts.
