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Newborn Screening Tests


What are newborn screening tests?

Newborn screening tests are tests given to infants just after they are born. These tests check for disorders that could cause serious harm. The tests are provided by your state’s department of health. Different states have different rules about which tests are done.

Newborn screening tests are accurate but they are not perfect. Sometimes they show that a child has a disease that the child does not actually have. This is particularly a concern when the true disease is very, very rare. Therefore all children who test positively for a disease should be tested again. Rarely, the tests do not identify children who actually do have a disease.

What diseases are tested for?

All states in the U.S. test for diseases in these categories:

  • Hemoglobin disorders. Tests can detect sickle cell anemia, hemoglobin C, and other blood disorders. Sickle cells can get stuck in blood vessels and block the flow of blood and oxygen to parts of the body. The lack of oxygen can damage the body tissues and cause severe pain and fever.
  • Endocrine disorders. Disorders such as congenital adrenal hyperplasia and hypothyroidism can be detected. Both of these disorders can seriously affect a baby and both are able to be well treated with medicines.
  • Cystic fibrosis. This disease affects the lungs and other organs and is helped by early treatment.
  • Galactosemia. This condition can cause blindness, mental retardation, and growth problems if not treated.
  • Biotinidase deficiency. This condition may lead to seizures, hearing loss, mental retardation, and problems with the immune system.
  • Phenylketonuria (PKU). This can cause mental retardation if not treated early.
  • Most states also screen for a variety of fatty acid, organic acid and amino acid disorders. Some examples of conditions screened for in all states are:
    • Homocystinuria. This causes mental retardation, blood clotting problems, and skeletal problems.
    • Maple syrup urine disease. Without treatment, this can cause severe mental retardation.
    • Glutaric academia. This condition varies widely in severity and may be helped by a diet that includes medical foods and formulas.

If these rare diseases are diagnosed early, some of them can be effectively treated. Some can be completely cured. Unfortunately some children will not improve very much from early diagnosis.

Hearing tests are also part of newborn screening in 35 states. The newborn needs to be quiet or asleep for this test. The test measures brain waves that result when a sound is made. Reduced hearing is a frequently occurring birth defect. If hearing loss is not treated early, speech, language and learning can be affected.

How are the tests done?

Your child's healthcare provider makes a tiny cut in the baby's heel to get a small amount of blood to test. Well infants are usually tested just before they go home from the hospital, but not later than 72 hours after birth. Sick or premature infants are tested at 1 week of age, or earlier if a disease is suspected.

If a test suggests your child has a disease, the health department will contact you and your baby's doctor. If the tests do not show any diseases, you will generally not be contacted. Your baby's doctor usually gets copies of the newborn screening test results.

If your baby needs a blood transfusion, blood tests should be done before the transfusion.

Some states provide a second set of newborn screening tests between 1 and 2 weeks of age. This is important if the newborn leaves the hospital less than 24 hours after birth.

Parents may refuse to have their newborn screened because of religious or personal beliefs. Parents who refuse to have the testing done must sign forms stating they refuse the tests.

You can get more information on newborn screening from your healthcare provider or from the state health department.


Written by Robert Brayden, MD, Professor of Pediatrics, University of Colorado School of Medicine.
Published by RelayHealth.
Last modified: 2011-02-22
Last reviewed: 2010-10-13

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a health care professional.

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