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Galactosemia Test

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Galactokinase enzyme test (blood) 1

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)


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.


  1. Fischbach F, Dunning MB III (2015). A Manual of Laboratory and Diagnostic Tests, 9th ed. Philadelphia: Wolters Kluwer Health.

  2. Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.

Other Works Consulted

  • Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

WebMD Medical Reference from Healthwise

Last Updated: August 07, 2014
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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