Newborn Screening Tests

by Darline Turner Lee, Physician Assistant, ACSM Exercise Specialist

Article Last Reviewed: Sept. 9, 2006

When infants are just days old, they have blood drawn for newborn screening tests to detect the presence of endocrine (hormonal), metabolic or hematological (blood related) disorders that could cause severe developmental damage or death. The tests are done early to identify the disorders and begin treatment before symptoms occur. In Texas, newborn screening tests are done twice-before the newborn leaves the hospital and by two weeks of age.

There are roughly 30 newborn screening tests that can be done. Each state follows different guidelines for newborn screening so the actual tests done on your child depend on the state in which you reside. In Texas, the newborn screening test contains the tests for PKU, CAH, congenital hypothyroidism, galactosemia and a hemoglobin test to look for sickle cell disease.

Phenylketonuria (PKU) - A rare autosomal recessive disorder (both parents must pass on the defective gene for the child to be affected). The amino acid phenylalanine is not properly metabolized because of the missing enzyme phenylalanine hydroxylase. Untreated, PKU causes brain damage resulting in severe mental retardation. Affected individuals must follow a strict diet extremely low in phenylalanine commonly found in milk, eggs and many other protein rich foods and in NutraSweet (aspartame). Close supervision by a physician or dietician is recommended.

Congenital Adrenal Hyperplasia (CAH) - Actually a group of endocrine disorders, CAH is the body’s inability to produce enough cortisol, an adrenal hormone. The body tries to compensate by producing more of other hormones. The particular hormone imbalances determine which type of CAH is present. The affected individual may have impaired development or difficulty healing from disease or injury. It is inherited as an autosomal recessive trait.

Treatment consists of hormone replacement to restore and maintain the physiologic balance to the endocrine system. Careful monitoring of hormone levels, development and response to illness and injury are essential.

Sickle Cell Anemia - Sickle cell anemia is a blood disorder prevalent among people of African and Mediterranean descent. It exists when hemoglobin, the oxygen-carrying molecule in blood, deforms into sickle shaped crystals and is unable to transport adequate amounts of oxygen to cells. The malformed, deoxygenated molecules cause blood clots leading to strokes, joint pain and damage to internal organs. There is no cure for sickle cell anemia. Treatment is aimed at reducing pain and preventing the potentially deadly complications. Sickle Cell Anemia is an autosomal recessive trait. A newborn with one abnormal hemoglobin S chain and one normal Hemoglobin chain is said to be a carrier and may exhibit few if any symptoms.

Congenital Hypothyroidism - Congenital hypothyroidism results in babies who are unable to produce adequate amounts of thyroid hormone. The most common causes are total or partial failure of the thyroid gland to develop or its development in an abnormal location. These types of hypothyroidism rarely recur in siblings.

Thyroid hormone is essential for normal growth and development, especially for normal brain growth. If untreated, congenital hypothyroidism results in mental retardation and stunted growth. Thyroid hormone replacement is easily given to infants in their food. The child must have regular follow up with an endocrinologist to monitor growth and to adjust medication dosages accordingly.

Galactosemia - Galactosemia, another autosomal recessive trait, develops when an infant is lacking enzymes necessary to metabolize galactose a major sugar of milk.

The baby appears normal at birth, but develops vomiting, diarrhea, lethargy, jaundice, and liver damage when milk-feedings are initiated. Left untreated, the disorder may result in death. Infants who survive may demonstrate developmental retardation, enlarged livers, kidney malfunction, growth failure and cataracts. These children must avoid all lactose and galactose containing foods. Consultation with a pediatric metabolic specialist is recommended.

Most diseases detectable by newborn screening tests are easily treated with specialized diets or with medications. With the serious complications and high death rates, it is difficult to understand why Texas screens for only 5 disorders.

Margaret Drummond-Borg, M.D. is the division director of genetic screening and case management for the Texas Department of Health (TDH). When posed this question, she replied,

“Over 300,000 infants are born in Texas each year. The TDH constantly evaluates various disorders to see if they should be added to the list of newborn screening. For a screening test to be added there has to be a rise in the incidence of the disorder, a screening test available that is both sensitive enough to detect the disorder and specific to that disorder and not be overly expensive.”

During the 2003 legislative session, the House and Senate both reviewed bills that would have amended the Texas Health and Safety Code. The bills lobbied for Tandem Mass spectrometers (MS/MS), devices that would allow TDH to screen for over 30 diseases in newborns. The bills required TDH to purchase 10 (MS/MS), each about $250,000, and to employ and train 18 people to begin performing the screenings within a year. TDH does not have the funds to implement the program and additional funding is not available. The cost of the machines, training the employees and the cost effectiveness of screening for the rare disorders was weighed against the costs of treating the disorders once symptoms manifest. The current budget deficits and special sessions have pushed this issue to a far back burner without resolution.

So what are parents to do? Avis Meeks Day, M.D., a pediatrician at the Austin Regional Clinic on South First Street suggests:

“Parents should obtain a good family history. If a close relative (a parent, sibling or close cousin) has a congenital disorder or had an infant with a congenital disorder, more screenings or actual definitive testing for specific disorders should be obtained.”

Pediatricians are on the front lines of diagnosing and treating these disorders and bear the brunt of parents’ anger and frustration when there is an adverse outcome.

“Sure the disorders are rare, say 1/50,000. But the odds don’t matter when it’s your child with a disorder that could have been avoided if we knew sooner to alter his diet or add a daily medication.”

Both Day and Drummond-Borg admit that parents have the option of requesting additional screening tests. There are private laboratories that run a wider array of newborn screening tests. Additional screening tests aren’t covered by insurance and require private payment.

Drummond-Borg added, “If parents want more information, they can obtain information and brochures on newborn screening from TDH or consult with a genetic counselor.”

Resources

The Texas Department of Health - http://www.tdh.state.tx.us/lab/nbs_about.htm

Save Babies Through Screening Foundation - www.savebabies.org.

Benefit Analysis of Universal Tandem Mass Spectrometry for Newborn Screening Schoen, E. et al, Pediatrics 2002; 110 781-786. Cost

The American Academy of Pediatrics - www.aap.org