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Galactose-1-phosphate uridyltransferase blood test
Galactosemia screen; GALT; Gal-1-PUT
Galactose-1-phosphate uridyltransferase is a blood test that measures the level of a substance called GALT, which helps break down milk sugars in your body. A low level of this substance causes a condition called galactosemia .
Galactosemia
Galactosemia is a condition in which the body is unable to use (metabolize) the simple sugar galactose.
How the Test is Performed
A blood sample is needed.
Blood sample
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
How the Test will Feel
When the needle is inserted to draw blood, some infants feel moderate pain. Others feel only a prick or stinging. Afterward, there may be slight bruising. This soon goes away.
Why the Test is Performed
This is a screening test for galactosemia.
In normal diets, most galactose comes from the breakdown ( metabolism ) of lactose, which is found in milk and dairy products. One out of 65,000 newborns lack a substance (enzyme) called GALT. Without this substance, the body cannot break down galactose, and the substance builds up in the blood. Continued use of milk products can lead to:
Metabolism
Metabolism refers to all the physical and chemical processes in the body that convert or use energy, such as:BreathingCirculating bloodControlling bo...
- Clouding of the lens of the eye ( cataracts )
-
Scarring of the liver (
cirrhosis
)
Cirrhosis
Cirrhosis is scarring of the liver and poor liver function. It is the last stage of chronic liver disease.
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Failure to thrive
Failure to thrive
Failure to thrive refers to children whose current weight or rate of weight gain is much lower than that of other children of similar age and gender....
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Yellow color of the skin or eyes (
jaundice
)
Jaundice
Jaundice is a yellow color of the skin, mucus membranes, or eyes. The yellow coloring comes from bilirubin, a byproduct of old red blood cells. Jau...
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Liver enlargement
Liver enlargement
Hepatomegaly is swelling of the liver beyond its normal size. If both the liver and spleen are enlarged, it is called hepatosplenomegaly.
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Intellectual disability
Intellectual disability
Intellectual disability is a condition diagnosed before age 18 that includes below-average intellectual function and a lack of skills necessary for d...
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This can be a serious condition if not treated.
Every state in the United States requires newborn screening tests to check for this disorder.
Normal Results
The normal range is 18.5 to 28.5 U/g Hb (units per gram of hemoglobin ).
Hemoglobin
Hemoglobin is a protein in red blood cells that carries oxygen. The hemoglobin test measures how much hemoglobin is in your blood.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
An abnormal result suggests galactosemia. Further tests must be done to confirm the diagnosis.
If your child has galactosemia, a genetics specialist should be consulted promptly. The child should be put on a no-milk diet right away. This means no breast milk and no animal milk. Soy milk and infant soy formulas are generally used as substitutes.
This test is very sensitive, so it does not miss many infants with galactosemia. But, false-positives can occur. If your child has an abnormal screening result, follow-up tests must be done to confirm the result.
Risks
Veins and arteries vary in size from one infant to another and from one side of the body to the other. Obtaining a blood sample from some infants may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin, causing bruising)
- Infection (a slight risk any time the skin is broken)
References
Chernecky CC, Berger BJ. Galactose-1-phosphate - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures . 6th ed. Philadelphia, PA: Elsevier; 2013:550.
Zinn AB. Inborn errors of metabolism. In: Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine Diseases of the Fetus and Infant . 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 99.
Review Date: 10/30/2016
Reviewed By: Anna C. Edens Hurst, MD, MS, Assistant Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
