Why It Is Done

• Identify newborns with galactosemia. Almost all babies born in the United States are tested for this disease. Many states require that newborns be tested for galactosemia.
• Determine whether infants and children with cataracts have galactosemia.
• Monitor the effect of diet therapy for people who have galactosemia.
• Detect carriers of galactosemia.

How To Prepare

No special preparation is required before having a

Discuss with your doctor any concerns you have about the need for the test, its risks, or how it will be done. Complete the medical test information form to help you understand the importance of the test.

How It Is Done

Tests for Blood sample from a heel stick

To check for the presence of galactose transferase enzyme, the heel of a newborn is pricked with a sharp instrument (lancet) and drops of blood are collected directly onto specially treated paper. The paper is then viewed under an ultraviolet light.

Blood sample from a vein

To measure the amount of galactose transferase in the blood, a sample of blood is taken from a vein in the arm. The health professional drawing blood will wrap an elastic band around your upper arm to temporarily stop the flow of blood through the veins of your arm. This makes it easier to put the needle into a vein properly because the veins below the band get larger and do not collapse easily.

The needle site is cleaned with alcohol and the needle is inserted. More than one needle stick may be needed if the needle does not get placed correctly or if the vein cannot supply enough blood.

When the needle is properly placed in the vein, a collection tube will be attached to the needle and blood will flow into it. Sometimes more than one tube of blood is collected.

When enough blood has been collected, the band around your arm will be removed. A gauze pad or cotton ball is placed over the puncture site as the needle is withdrawn. Pressure is applied to the puncture site for several minutes and then a small bandage is often placed over it.

Urine sample

To test for sugar galactose in a urine sample from a baby, a health professional will tape a plastic collection bag to the baby's genital area. After the baby urinates, the collection bag is removed.

How It Feels

Blood sample from a vein

You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. However, many people do not feel any pain (or have only minor discomfort) once the needle is positioned in the vein. The amount of pain you feel depends on the skill of the health professional drawing the blood, the condition of your veins, and your sensitivity to pain.

Blood sample from a heel stick

A baby will usually feel a brief stinging pain when the lancet pricks the skin for a heel stick. While the blood is being collected, there is little or no discomfort.

Urine sample

A baby will usually feel no discomfort from the use of a urine collection bag; however, removing the tape that attaches the bag to the skin may cause temporary discomfort.

There is very little risk of complications from having blood drawn from a vein or a heel stick. A small bruise may develop at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the blood is collected.

Rarely, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated by applying a warm compress several times daily.

Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medications can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medication, tell the health professional before your blood is drawn.

There is very little risk of complications when collecting a urine sample from a baby. Removing the tape that holds the bag in place may cause mild skin irritation.

Galactokinase enzyme test (blood)

• A recent blood transfusion may cause inaccurate results.

• Rough handling, contamination, or inadequate refrigeration of the blood sample can cause inaccurate test results.

• Improper placement of a urine collection bag on an infant may result in an inadequate sample of urine collected.

Test Results

What Affects the Test.

What To Think About

• The blood sample for a
• A urine test for galactosemia is available for use in the hospital setting. Although the results are available immediately, the test is less accurate than the blood test. If a urine test is done, a blood test is needed to confirm the diagnosis.
• It is not uncommon for a test that checks for the presence of galactose or galactose transferase enzyme to be falsely positive (indicating a baby has galactosemia when the disease is not present). Positive results from one of these tests needs to be followed by measuring the amount of galactose transferase enzyme in the blood. The baby's diet should be changed until results of the blood test confirm the presence or absence of the disease.
• If test results confirm that a child has galactosemia, the parents will receive counseling about the type of foods their child should avoid. A substitute for milk and milk-based formula will prevent damage caused by galactosemia. A child who has galactosemia must avoid dairy products for the rest of his or her life.
• If one or both parents know that they may pass galactosemia on to their child, the child should be tested at birth. The parents may want to undergo genetic counseling to learn about the disease and the likelihood of passing it to their children. In countries where newborn screening for galactosemia is not routinely done:
  • If both parents are galactosemia carriers , the child should be tested at birth.
  • If only one parent is a galactosemia carrier, the child has a 50% chance of being a carrier and should be offered testing in adulthood.
• A pregnant woman may need to follow a galactose-free diet if her baby is at risk for galactosemia.