Galactosemia screen; GALT; Gal-1-PUT DefinitionGalactose-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. How the Test is PerformedA blood sample is needed. How the Test will FeelWhen 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 PerformedThis 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:
This can be a serious condition if not treated. Every state in the United States provides newborn screening tests to check for this disorder. Normal ResultsThe normal range is 18.5 to 28.5 U/g Hb (units per gram of hemoglobin). 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 MeanAn 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. RisksThere is little risk in taking blood from an infant. 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:
ReferencesChernecky CC, Berger BJ. Galactose-1-phosphate - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:550. Patterson MC. Diseases associated with primary abnormalities in carbohydrate metabolism. In: Swaiman KF, Ashwal S, Ferriero DM, et al, eds. Swaiman's Pediatric Neurology. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 39. | |
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Review Date: 10/13/2022 Reviewed By: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited. | |
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