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Blood test for galactosemia
Last reviewed: 04.07.2025
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Reference values (norm) for galactose concentration in the blood of newborns are 0-1.11 mmol/l (0-20 mg%), at an older age - below 0.28 mmol/l (5 mg%).
Galactosemia is caused by a deficiency of galactose-1-phosphate uridyltransferase (classical galactosemia ) or, less commonly, galactokinase or galactose epimerase.
To screen for galactosemia, the bacterial growth inhibition method is used. The study is conducted in newborns, for which blood is taken from the umbilical cord or from a finger on filter paper. Inhibition of bacterial growth is directly proportional to the concentration of galactose in the blood (normally, growth inhibition does not occur).
In quantitative determination, blood serum or urine is examined. In the presence of the disease, the concentration of galactose in the blood can increase to 11.25 mmol / l (300 mg%). Quantitative determination of galactose in the blood is important for assessing the adequacy of the selection of a diet for the patient. With a properly selected diet, the level of galactose in the blood should not exceed 0.15 mmol / l (4 mg%). In healthy newborns, the concentration of galactose in the urine is below 3.33 mmol / day (60 mg / day), subsequently - below 0.08 mmol / day (14 mg / day). In patients with galactosemia, the content of galactose in the urine is 18.75-75 mmol / l (500-2000 mg%).
Currently, there are diagnostic kits that allow quantitative determination of the activity of galactose-1-phosphate uridyltransferase in red blood cells. This study not only allows the presence of enzyme deficiency to be established, but also the identification of heterozygous carriers of the defective gene.
Galactose is elevated in liver diseases, hyperthyroidism, and digestive disorders.
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