Galactosemia screen
Key points
- This is a blood test that measures the level of GALT, an enzyme involved in breakdown of milk sugars (lactose/galactose).
- Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand.
- For infants and children: The preparation you can provide for this test depends on your child's age, previous experience, and level of trust.
- In normal diets, the major source of galactose is in the metabolism of lactose.
Alternative names
Galactose-1-phosphate uridyltransferase; GALT; Gal-1-PUT
Definition
This is a blood test that measures the level of GALT, an enzyme involved in breakdown of milk sugars (lactose/galactose).
How the test is performed
Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip of paper, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test
No special preparation is necessary.
For infants and children:
The preparation you can provide for this test depends on your child's age, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics:
- infant test or procedure preparation (birth to 1 year)
- toddler test or procedure preparation (1 to 3 years)
- preschooler test or procedure preparation (3 to 6 years)
- schoolage test or procedure preparation (6 to 12 years)
- adolescent test or procedure preparation (12 to 18 years)
How the test will feel
When the skin is pricked with the needle, the amount of discomfort varies. Some people experience moderate pain while others feel only a prick or stinging sensation. Afterward, the site may be bruised for a few days.
Why the test is performed
This is a screening test for galactosemia.
In normal diets, the major source of galactose is in the metabolism of lactose. The major source of dietary lactose is milk and dairy products. In most people, galactose is converted to glucose by a series of chemical reactions. Each chemical reaction is catalyzed by an enzyme.
Written and revised by
Gerald Hurowitz, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.