Children's Health

Galactose is a sugar that is part of the lactose found in milk and milk products. A galactosemia test is a blood or urine test that checks for enzymes that are needed to change galactose into glucose, a sugar that your body uses for energy. A person with galactosemia doesn't have one of these enzymes, so high levels of galactose build up in the blood or urine.

When galactose builds up in a baby's blood, it can cause brain damage, seizures, and intellectual disabilities. The damage caused by galactosemia can begin within weeks after the baby has started drinking breast milk or formula. Babies with galactosemia need foods low in galactose in order to gain weight and to prevent brain damage, liver problems, infection, and cataracts.

Galactosemia is a rare disease that is passed from parents to children (inherited genetic disorder). A galactosemia test is usually done to determine whether a newborn has the disease. In a family with a member who has galactosemia, a genetic test can be done on adults to determine whether they have an increased chance of having a child with the disease.

Why It Is Done

A galactosemia test is done to:

• Determine whether a newborn has the enzymes needed to change galactose into glucose.
• Monitor the effectiveness of diet changes for a child with galactosemia.

How To Prepare

No special preparation is required before having this test.

Talk to your doctor about any concerns you have about the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

Tests for galactosemia are done on a blood or urine sample.

Blood sample from a heel stick

If galactosemia testing is done on a baby, a heel stick will be done instead of a blood draw from a vein. For a heel stick blood sample, several drops of blood are collected from the heel of the baby. The skin of the heel is cleaned with alcohol and then punctured with a sterile lancet. Several drops of blood are collected inside circles on a specially prepared piece of paper. When enough blood has been collected, a gauze pad or cotton ball is placed over the puncture site. Pressure is maintained on the puncture site briefly to stop the bleeding, and then a small bandage is usually applied. A blood sample is usually collected within 2 to 3 days after birth.

If the test shows that the baby has galactosemia, the results will be confirmed on a blood sample taken from a vein.

Blood sample from a vein