Definition of Newborn screening tests:

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.

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