Heel Stick - Genetic Screening for Newborns
Skin Prick Blood Test Detects Rare and Potentially Fatal Disorders
May 15, 2009
The heel stick test was invented in 1923 by Danish pediatrician, Paul Drucker, and is now the most commonly used method for drawing blood from newborns. With just one prick of a needle into a baby’s foot, doctors can screen for a myriad of hereditary ailments, and get results within days after birth.
While many genetic disorders are rare (including those of the blood, endocrine and metabolic systems), the test is strongly endorsed by such organizations as the American College of Medical Genetics and the American Academy of Pediatrics. If left untreated, genetic diseases can result in extreme physical disability, mental incapacitation, and even death.
How a Heel Stick is Performed
A heel stick is urged within the first five days after birth. The procedure, sometimes alternatively referred to as the heel prick, is relatively simple and virtually non-invasive. A medical practitioner, nurse, midwife, or trained phlebotomist, will cleanse the plantar surface of the infant’s heel with antiseptic before making a microscopic puncture with a sharp needle, lancet, or narrow-gauge instrument ("capillary"), and draw a few drops of blood. The sampling, or “blood spot,” is collected on a slide, or a strip, or placed onto marked areas of an absorbent card. For optimum results, the sample must dry at room temperature for at least four hours before being forwarded on for laboratory analysis.
Incidences of false positives – due to testing too early, or by other factors—require that some infants undergo a retest. This does not necessarily mean that there is a diagnosed disorder, but rather that the possibility exists. Nonetheless, a retest should be conducted to assuage fears, or to begin any necessary treatments as soon as possible.
Why Newborn Genetic Screens Are Important
Statistics show that one out of every 1,500 babies born will develop one of the disorders detectable through newborn screening. Since most newborns appear normal, there is no way of knowing if the child has a metabolic, or genetic, disorder until outward symptoms appear. By then, it may be too late to halt or reverse the effects. Testing is recommended also because there may be no history or knowledge of genetic disorders within a family.
The fact is, most children with these disorders come from families where there is no previous history. As a precautionary measure, more than 95% of the roughly 4 million children born annually in the United States now undergo the heel stick test. The emphasis is on early detection, since most metabolic and endocrine illnesses respond remarkably well to pharmaceutical or nutritional treatment.
The Disorders Heel Stick Tests Detect
Though all states require screening for at least 21 of the 29 most debilitating endocrine and metabolic diseases, there are more than 50 disorders that can be detected through newborn screening. However, each individual state determines which disorders will be screened. Common tests for babies in the U.S. include those for sickle cell disease, congenital hypothyroidism , Phenylketonuria , or PKU (amino acid overproduction leading to brain damage), and Cystic Fibrosis (CF). Undiagnosed and unattended to, these diseases can bring on liver disease, cataracts, jaundice, chronic respiratory and bacterial infections, stunted growth, mental retardation, brain damage and diminished life expectancy.
Any new parent with questions about genetic screening should consult a primary care physician, obstetrician, or pediatrician. More information is available through the National Newborn Screening and Genetics Resource Center and the March of Dimes. The point is to identify life threatening disorders expediently so that treatment may commence at the earliest interval to spare families undue distress and to save lives.
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