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Newborn Screening

By Esther Entin, MD

Newborn screening is one of the great medical successes of the 21st century. It stands alongside vaccination and the reduction in smoking in its impact on public health.(1) Screening is the practice of testing every newborn for certain harmful or potentially fatal conditions. Infants are typically screened at birth for hearing loss and certain genetic, endocrine, and metabolic disorders that would otherwise go undetected until it was too late.

Screening for Life-Threatening Conditions

A recent report in the Morbidity and Mortality Weekly updates the current status of the United States Newborn Screening program and notes that although the program is highly successful and greatly expanded from its original scope, there is still room for improvement. Screening technology lags in some states, and there may be no immediate or long-term management of infants identified with abnormal conditions.(2)

Parents-to-be should understand that the goal is to screen for conditions for which very early intervention can significantly change long-term outcomes. Most of these conditions can be identified by a blood test, which is obtained before discharge from the nursery or within 1-2 weeks of life if the infant leaves the hospital sooner than 24 hours.

The ability to follow up on positive tests efficiently for final diagnostic confirmation, and the ability to provide appropriate medical care and guidance to avert potential consequences of the identified condition are critical to any screening program. The tests that are currently done identify conditions in which changes in diet, use of medication, increased medical surveillance, and early intervention can all prevent or ameliorate poor outcomes such as poor growth, severe developmental delay, organ damage, and death.

Some of these conditions require lifelong interventions. For example, individuals with PKU must follow a low phenylalanine diet throughout their lives, but in doing so can avoid mental retardation. People with congenital hypothyroidism can have normal growth and development by taking oral thyroid hormone supplement.

Those with sickle cell disease can avoid life-threatening infections with prophylactic antibiotic. Those with hearing loss can be remediated early to help promote language development. One estimate puts the cost of screening for congenital hypothyroidism at $5 per infant. Though it is difficult to determine the cost-benefit exactly, one study found the potential health benefit of testing 4 million infants for congenital hypothyroidism was a total gain of nearly 15,000 IQ points.(3)

Background and History

Newborn screening in the United States began in the 1960s with the advent of screening for phenylketonuria (PKU) and congenital hypothyroidism. It is a state-based system that involves screening, diagnostic follow up, education, and of course, treatment.

State laboratories receive training, support, technical assistance, and consultation from the Centers for Disease Control in the form of a quality assurance program. In 2006 a group convened by the American College of Medical Genetics recommended a uniform screening panel of 29 core conditions. States, basing their decision on the risks, benefits and costs of the screening test, have the final say as to what tests to include in their panel. When additional conditions are identified as candidates for screening, they are nominated and reviewed for inclusion by the Advisory Committee on Hereditable Disorders in Newborns and Children.

Screening for an Expanding List of Conditions

Severe Combined Immunodeficiency (SCID)
In 2010, based on panel recommendations, the Secretary of Health and Human Services recommended that severe combined immunodeficiency (SCID) be included in the panel of newborn screening tests. SCID is a primary immunodeficiency disease, sometimes known as "bubble-boy syndrome." Affected infants lack certain kinds of blood cells that help resist infections caused by a variety of viruses, bacteria and fungi. These babies look healthy when they are born, but if they are not treated early, most often by bone marrow transplant from a healthy donor, they cannot survive. This recommendation has been adopted by many states, most recently Washington, Florida, Texas, and Colorado.

Critical Congenital Heart Disease
Similarly, screening for critical congenital heart disease (CCHD) was added to the list of recommended tests in 2011. These seven specific conditions that stem from major abnormalities in the anatomy of the heart and great vessels. Each requires treatment soon after birth to prevent severe disability or death. They are hypoplastic left heart syndrome, pulmonary atresia (with intact septum), tetralogy of Fallot, total anomalous pulmonary venous return, transposition of the great arteries, tricuspid atresia, and truncus arteriosus.

The test for CCHD is a painless measurement of the baby’s blood oxygen and pulse which is done by attaching sensors to the skin. If a screening test shows a problem, the baby would be followed up for complete diagnosis by a pediatric cardiologist. A normal test does not rule out all potential cardiac problems in newborn infants but it helps to identify those infants who need emergency treatment for the seven CCHDs.

There are about 4 million newborns in the US each year and about 98% of them of screened. Of these about 12,500 are diagnosed with one of the core 29 conditions. The most common are: hearing loss, primary congenital hypothyroidism, cystic fibrosis, sickle cell disease, and medium chain acyl-Co A dehydrogenase deficiency.

In May 2011, the MMWR included newborn screening among the ten great public health achievements in the US between 2001 and 2012.(1) They noted that, "Improvements in technology and endorsement of a uniform newborn-screening panel of diseases have led to earlier life-saving treatment and intervention for at least 3,400 additional newborns each year with selected genetic and endocrine disorders." In 2003, all but four states were screening for only six of these disorders. By April 2011, all states reported screening for at least 26 disorders on an expanded and standardized uniform panel. Newborn screening for hearing loss increased from 46.5% in 1999 to 96.9% in 2008.

The Message for Parents: Don't Take Screening for Granted, Follow-Up

This year, the MMWR report identified several “critical gaps” and challenges in the current newborn screening program. These include a shortage of experts who are trained to diagnose and manage the conditions that are detected by screening and the need to improve laboratory technology to reduce testing costs, increase accuracy of testing, and expand the scope of possible tests. There is also insufficient public education about the importance of newborn screening and too little follow-up in some cases. Ironically, the success of screening has created a problem. According to the report, “screening is not enough – it is critical to avoid complacency in assuming that every newborn who is screened will receive optimal service and care. Short-term follow up and management of children with disorders and long term follow up activities within the entire newborn screening system are central to realizing the promise of newborn screening.“

If a baby has been discharged before 24 hours of age, or born at home, parents should talk to their doctors about obtaining a newborn screening test within 1-2 weeks of their birth.

Simply put, early identification is only step one in the lives of diagnosed children whose resultant medical and psychosocial challenges must be managed throughout their lifetimes.

Parents may want to ask their doctors about their babies’ newborn screening tests and confirm that they were done. Typically, parents are not informed of the results unless they are abnormal or need to be repeated for some reason. If a baby has been discharged before 24 hours of age, or born at home, parents should talk to their doctors about obtaining a newborn screening test within 1-2 weeks of their birth.

When notified of a test abnormality, parents should contact their baby’s doctor for follow up as soon as possible as early identification and treatment is key to preventing bigger problems. Parents can determine what tests their state does by asking their doctor, contacting their local health department. The CDC offers information here.

August 15, 2012



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