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Screening Tests for Newborns

Overview

In the United States, routine evaluation of a newborn includes a number of laboratory tests. These tests are valuable because they have the potential to identify diseases and disorders before symptoms appear. Early detection allows treatment that may prevent development of serious problems.

Newborns can now be screened for up to 55 conditions and diseases. Most of the screening tests are done on a spot of blood obtained from a prick of the heel. A single blood sample can be used to perform many different tests at the same time.

The types of conditions and diseases for newborn testing fall into three basic categories.

• Screening tests for congenital disorders: A panel of 29 tests is recommended for all newborns. Many states mandate that all 29 be done on every newborn; other states mandate some, but not all, of these tests.

• Tests for infectious diseases: Testing for infectious diseases is typically done on newborns only when it is known that the mother has been exposed to certain infectious agents or if the newborn exhibits symptoms consistent with an infectious disorder.

• Tests for inherited (genetic) disorders: Genetic testing is most often done on newborns who are at increased risk because of family history or ethnic background. The testing is for the specific gene(s) associated with a disorder that occurs in the family or with high frequency in members of the specific ethnic group.

What Are Screening Tests?

Screening tests are laboratory tests that are used to identify individuals with or at increased risk for a particular condition or disease before they may even be experiencing symptoms or realize they may be at risk. The information derived from these tests can be used to counsel patients about their risks or likelihood of developing the condition or disease. Screening tests also help to detect disease in its earliest and most treatable stages. Therefore, screening tests are most valuable when they are used to screen for diseases that are serious and treatable, so that there is a benefit to detecting the disease before symptoms begin. They should be sensitive, that is, able to correctly identify those individuals who have a given disease. A positive screening test often requires further testing with a more specific test, which can correctly exclude those individuals who do not have the given disease, in order to confirm a diagnosis. Many routine tests performed at regular health exams fall into the screening category, such as cholesterol testing and Pap smears for women. Newborns are screened for a variety of conditions at birth.

A diagnostic test may be used for screening purposes, although a diagnostic test is generally used to confirm a diagnosis in an individual who usually has signs, symptoms, or other evidence of a particular disease.

Routine Tests: Congenital Disorders

In 2006, long-awaited national guidelines on newborn screening were announced by the American College of Medical Genetics. The 29 recommended tests help identify potentially treatable congenital disorders within days of birth. Life-threatening health problems, mental retardation, and serious lifelong disabilities can be avoided or minimized if a problem is quickly identified and treated.
The 29 disorders for which routine testing has been recommended are listed in the table and are organized by broad categories, such as metabolic disorders subdivided by what kind of substance is affected (an amino acid, a sugar molecule, or a hormone), hemoglobin disorders (called hemoglobinopathies), and other disorders.
All states require three of these tests: phenylketonuria (PKU), congenital hypothyroidism (CH), and galactosemia (GAL); at least 33 states require cystic fibrosis (CF) tests. Many states require all 29.

What to Ask

Ask your healthcare provider (obstetrician, midwife, pediatrician) which tests will be routinely done and which supplemental tests may be appropriate for your newborn. The instructor of your childbirth education classes, a nurse at the hospital or birthing center, or your state health department can also give you more information.

Physicians and parents may request a “supplemental newborn screening” panel in addition to the state-required tests. At some hospitals, you can indicate your preference for this more extensive testing when you check in for the birth. Supplemental newborn screening tests can also be arranged, in advance of the birth, through one of several private laboratories offering this service.

Parents should also be aware that special collection techniques are used with newborns to minimize discomfort during specimen collection. In most cases, all the tests can be done using just a few drops of blood obtained from a pricked heel. Ordering the supplemental tests will not require extra sticks or blood from your newborn.

As more screening tests for newborns are implemented by states, more test results will necessitate follow-up. The significance of these tests usually requires that each positive result be confirmed by another test. If the results of a screening test are abnormal, ask your health care provider to tell you about the test’s reliability and limitations and what should be done to verify the finding.

If At Risk

Inherited (Genetic) Disorders

Genetic tests fit into three categories: those considered because of a family history of the disease, those considered because the disease is common in the family’s ethnic groups, and those that may be random or be indicators of a future risk.

• Family history: When parents are concerned that a certain disease runs in their families (for example, Duchenne muscular dystrophy, cystic fibrosis, fragile X syndrome, or other chromosome disorders), they may request that their newborn be tested for the disease. Often, a screening test can be done during pregnancy instead of after birth. While testing for cystic fibrosis may be ordered because of family history, its frequency in the population at large means that testing is now recommended for all newborns, and many states include this test in their newborn screening panel.

• Ethnic group: When parents are concerned because a certain disorder is common among their ethnic groups (for example, Tay-Sachs disease, thalassemia, sickle cell anemia, cystic fibrosis, or congenital adrenal hyperplasia (CAH)), they may request that their newborn be tested. In this case, too, the parents may prefer, if possible, to have a screening test done during pregnancy instead of after birth. The national standards announced in 2006 by the American College of Medical Genetics advise screening all newborns for sickle cell anemia, hemoglobin S/beta-thalassemia, cystic fibrosis, and CAH. Currently, almost all states screen newborns for sickle cell anemia, and many screen for CAH and cystic fibrosis.

• Other risks: Less frequently, some parents request that their newborn’s DNA be tested to identify a condition that may not become evident or have an effect until later in life (for example, Huntington disease, type 1 diabetes, and some forms of breast, ovarian, and colon cancer). Some parents value the information and want to be on the lookout for improvements in diagnosis, prevention, and treatment.

In some cases, one or both of the parents can be tested before or during a pregnancy to determine if they are carriers of these gene-based disorders. Fluids from the fetus can also sometimes be tested during the pregnancy to detect suspected conditions.
Genetic tests can be run on various types of body fluids and tissues. DNA testing, for example, can be done on a tiny sample of blood, skin, bone, tissue, or even hair. For some conditions, chromosomes are examined for abnormalities; for other diseases, a single gene is analyzed. It should be noted that some genetic tests will identify a condition for which there is no treatment or cure and no changes can be made to improve the child’s quality of life. The value of such test results is controversial.

Infectious Diseases

TORCH Panel

Newborns who have certain symptoms or who are born to mothers who may have been exposed to certain pathogens may be screened for toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus. These four tests also may be run as a panel known as a TORCH screen. Newborns may be screened for other infections, such as syphilis, hepatitis B, enterovirus, Epstein-Barr virus, varicella-zoster virus, and human parvovirus.

HIV Testing

In the United States, newborns are likely to be screened for HIV infection if their mothers were not tested when they were pregnant (see HIV Screening during Pregnancy). Human immunodeficiency virus is the virus that causes AIDS (acquired immunodeficiency syndrome). The infection can pass from an infected mother to her child during birth (when exposed in the birth canal to the mother’s secretions and blood) or during breastfeeding (when the infant drinks breast milk containing the virus).

More than 90% of all AIDS cases in children in the United States came from the mother during pregnancy. In 2005, about 142 children were infected with HIV from their mothers in this country, reported the U.S. Centers for Disease Control and Prevention. If a mother with HIV does not receive treatment during the pregnancy, the child has a 1 in 4 chance of getting AIDS. With timely treatment, fewer than 2% of children of infected mothers get the disease.

Thanks to aggressive screening and early intervention, the United States has seen a steady decline in new AIDS cases in children. The best way to protect the child’s health is to detect the HIV infection during pregnancy, treat the mother with medication, and make birthing plans to help the baby avoid infection. If the mother was not tested during pregnancy or childbirth, the newborn can be screened and treated shortly after birth. HIV testing has become routine prenatal care in this country; some states even require that all pregnant women or their newborns be tested.

• Screening the mother: All pregnant women in the United States should be counseled about HIV early in their pregnancy and receive voluntary HIV testing to protect the child’s health. This is the recommendation of many groups, including the U.S. Public Health Service, American Academy of Pediatrics, American College of Obstetricians and Gynecologists, and U.S. Preventive Services Task Force.

• Screening the baby: In the United States, if the mother’s HIV status is not determined before or during pregnancy or during labor and delivery, health care providers recommend that the newborn be given an HIV test within 24 hours of the birth (in a few states, this is a requirement). Treatment begun within 48 hours of birth helps prevent a baby who was exposed to the virus from becoming infected.

Content last reviewed in March 2008. |  This page was last modified in November 2011.