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Galactosemia Test

Results

A galactosemia test is a blood or urine test that checks for the enzymes that are needed to change galactose into glucose, a sugar that your body uses for energy.

Galactose tests (blood or urine)
Normal:

Negative (galactosemia is not present)

Abnormal:

Positive (galactosemia is present)

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Galactose-1-phosphate uridyltransferase (GALT) test (blood)
Normal:1

18.5–28.5 units per gram (U/g) of hemoglobin (1.19–1.84 milliunits per mole of hemoglobin [mU/mol Hb]): The person does not have galactosemia.

Abnormal:2

Less than 5 U/g of hemoglobin (less than 0.32 mU/mol Hb): The person has galactosemia.

5–18.5 U/g of hemoglobin (0.32–1.18 mU/mol Hb): The person may be a carrier of galactosemia and able to pass the disease on to his or her child.

Galactokinase enzyme test (blood)1
Normal:

Adults: 12–40 milliunits per gram of hemoglobin (mU/g Hb) (200–667 pkat/g Hb)

Children 2–18 years: 11–54 mU/g Hb (183–900 pkat/g Hb)

Children 0–2 years: 11–150 mU/ g Hb (183–2500 pkat/g Hb)

Abnormal:

Lower-than-normal values, depending on age

A newborn screening test that shows the baby has an increased risk of galactosemia will be confirmed by other tests.

Many conditions can change galactose levels. Your doctor will discuss any significant abnormal results with you in relation to your baby's symptoms and past health.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • A blood transfusion.
  • Improper placement of a urine collection bag on a baby.

What To Think About

  • Early detection and treatment of galactosemia is very important, because the disease can cause brain damage, liver failure, and cataracts if it is not treated. Within 24 hours of drinking breast milk or formula, galactose blood levels in a baby with galactosemia start to rise. A galactosemia test 2 to 3 days after birth will show whether your baby has galactosemia. Almost all states in the United States have laws that require galactosemia testing of newborns within a few days of birth.
  • If your baby's test is positive, the test will be repeated to confirm the diagnosis.
  • If test results confirm that your baby has galactosemia, ask to speak to a dietitian. A substitute for breast milk or milk-based formula, such as formula made from soy, will prevent damage caused by galactosemia. It will never be safe to give milk or milk products to a child who has galactosemia.
  • If you or your partner knows that you are a carrier of galactosemia or if you have family members with galactosemia, you may want to have genetic counseling to learn about the disease and the likelihood of passing it to your children. To learn more, see the topic Genetic Test.

WebMD Medical Reference from Healthwise

Last Updated: November 29, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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