Newborn screening tests are medical tests performed on babies shortly after birth to identify certain genetic, metabolic, hormonal, and functional conditions that aren’t apparent at birth but can lead to serious health problems if left untreated.
Most screening tests are performed 24-48 hours after birth, typically before the baby leaves the hospital.
The main test involves:
A few drops of blood taken from the baby’s heel. The blood is placed on special filter paper and sent to a laboratory Results usually come back within 1-2 weeks
The specific conditions tested commonly include:
Metabolic disorders Metabolic disorders – Amino acid disorders Phenylketonuria (PKU) Maple syrup urine disease (MSUD) Homocystinuria (HCY) Citrullinemia type I (CIT) Argininosuccinic aciduria (ASA) Tyrosinemia type I (TYR I) Metabolic disorders – Fatty acid oxidation disorders Medium-chain acyl-CoA dehydrogenase deficiency (MCAD) Very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) Long-chain L-3-hydroxyacyl-CoA dehydrogenase deficiency (LCHAD) Trifunctional protein deficiency (TFP) Carnitine uptake defect (CUD) Metabolic disorders – Organic acid disorders Propionic acidemia (PROP) Methylmalonic acidemia (mutase deficiency & cobalamin Isovaleric acidemia (IVA) Methylcrotonyl-CoA carboxylase deficiency (3-MCC) 3-Hydroxy-3-methylglutaric aciduria (HMG) Holocarboxylase synthase deficiency (MCD) β-Ketothiolase deficiency (BKT) Glutaric acidemia type I (GA I)
These disorders affect how the body processes nutrients.
Endocrine disorders- Congenital hypothyroidism and congenital adrenal hyperplasia, which involve hormone production problems.
Hemoglobin disorders -Sickle cell disease and thalassemia, which affects red blood cells.
Sickle cell anemia (Hb SS) Hb S/β-thalassemia Hb SC disease Other clinically significant hemoglobinopathies
Functional conditions- Critical congenital heart defects screened using pulse oximetry, and hearing loss screened with hearing tests.
Other genetic conditions-Cystic fibrosis, severe combined immunodeficiency (SCID), and spinal muscular atrophy in some locations.
The Recommended Uniform Screening Panel (RUSP) includes over 37 core conditions and over 25 secondary conditions.
Most U.S. states screen for all or nearly all of these.
Other diseases:
Biotinidase deficiency Classic galactosemia (GALT) Critical congenital heart disease (CCHD) – pulse oximetry Hearing loss – universal newborn hearing screening (not blood spot)
Pompe disease (glycogen storage disease type II) Mucopolysaccharidosis type I (MPS I, Hurler syndrome) X-linked adrenoleukodystrophy (X-ALD) Spinal muscular atrophy (SMA) Guanidinoacetate methyltransferase deficiency (GAMT) Mucopolysaccharidosis type II (MPS II, Hunter syndrome) T-cell related lymphocyte deficiencies (beyond SCID)
Early detection allows for immediate treatment before symptoms develop, which can prevent intellectual disabilities, serious illness, or death.
Many of these conditions are treatable if caught early but can cause irreversible damage if diagnosis is delayed.