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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. Most of these illnesses are very rare, but are treatable if caught early.
In the United States, individual states regulate newborn screening, so the diseases screened for vary considerably from state to state. 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).
In addition to the newborn screening blood test, a hearing screen is recommended for all newborns.
Alternative Names
Infant screening tests; Neonatal screening tests; The PKU test
How the Test is Performed
Blood tests: A health care professional will prick the baby’s heel to obtain a few drops of blood. The blood is sent to a lab for analysis.
Hearing test: A health care provider will place a tiny earpiece or microphone in the infant’s ear or stick electrodes on the baby’s head while the baby is quiet or asleep.
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. Studies have shown that babies whose moms hold them skin-to-skin or breastfeed them during the procedure show less distress. Swaddling the baby, or offering a pacifier dipped in sugar water, also appear to help reduce pain.
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.
If follow-up testing confirms that the child has a disease, 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 (see also: Neonatal cystic fibrosis screening)
- 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)
- 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: Hearing loss - infants
Normal Results
Normal values for each screening test may vary depending on how the test is performed.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
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.
Although states do not perform all screening 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.
Morrow C et al. Reducing Neonatal Pain during Routine Heel Lance Procedures. MCN, The American Journal of Maternal/Child Nursing, November/December 2010; (35)6:346 – 354.
Smith L. Updated AAP Guidelines on Newborn Screening and Therapy for Congenital Hypothyroidism. Am Fam Physician. 2007; 76(3).
Levy PA. An overview of newborn screening. J Dev Behav Pediatr. 2010 Sep;31(7):622-31.
Reviewed By: Kimberly G Lee, MD, MSc, IBCLC, Associate Professor of Pediatrics, Division of Neonatology, Medical University of South Carolina, Charleston, SC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
