There are many reasons for baby's 'heelstick' tests

Tots to Teens

April 23, 1996|By Dr. Modena Wilson and Dr. Alain Joffe | Dr. Modena Wilson and Dr. Alain Joffe,SPECIAL TO THE SUN

We just brought our first baby, a boy, home from the hospital. I noticed now that he has several small scabs on his heels. My wife said they needed to draw blood, but she doesn't remember why. Do you know why? Will the marks go away?

There are at least five tests on capillary blood that can be obtained from a "heelstick." Most newborns have more than one of these, but let's start with one all babies should have.

After a baby is feeding, but before leaving the hospital, all babies should have blood drawn for a "hereditary metabolic screen." This blood is sent on special filter paper to the state laboratory to be tested for certain inherited diseases that require speed diagnosis and therapy.

One of these tests, the first done in this way, is for phenylketonuria (PKU). This blood drawing is often still referred to as the PKU test, even though tests for a number of additional diseases are now included. This hereditary metabolic screen will need to be repeated by your pediatrician sometime in your baby's first month, after he has been feeding even longer.

Many newborns will also have at least one glucose (blood sugar) test during the first few hours of life to make certain their blood sugar is not low. A low value is called hypoglycemia, and when found, the baby is fed more frequently. Extreme hypoglycemia can cause seizures.

If a baby's color is especially red or pale, a test of red blood cells may be measured to make certain he does not have too many (polycythemia) or too few (anemia). Either can cause the baby to be sluggish and sometimes needs to be treated.

Bacterial infection attacks newborns more commonly than older children and is quite serious when it occurs. Symptoms of infection in newborns are often quite subtle. If symptoms are noted, or if a baby is considered at extra risk for developing a bacterial infection -- for example, because his mother is febrile or membranes ruptured many hours before delivery -- blood may be obtained to measure the number and kind of white blood cells. White blood cells help fight infection. White blood cell tests help the doctors decide whether the baby should be treated with antibiotics.

Finally, some babies have blood drawn to test their bilirubin level. Bilirubin makes a baby's skin and eyes look yellow. The baby is said to be jaundiced. Bilirubin accumulates in babies because their livers are not yet working perfectly. Very high levels of bilirubin are treated by putting babies under lights that emit a wavelength that helps break down bilirubin.

No doubt your son got one or more of these tests. Your pediatrician will be able to tell you which ones and why. As far as the marks are concerned, they will fade. They may always be detectable if you search, because a bit of scar tissue is left behind. However, they won't look nearly so prominent when he wears size 11 shoes.

Dr. Wilson is director of general pediatrics at Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.

Pub Date: 4/23/96

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