Three types of enzymatic deficiencies, galactokinase, galactose-1-phosphate uridyltransferase (GPUT), and uridine diphosphate (UDP) galactose-4-epimerase are responsible for galactosemia, an autosomal recessive inborn error of galactose metabolism. Clinical Information: The most common form of galactosemia (classic galactosemia) is caused by homozygous inheritance of abnormal GPUT phenotypic designation (GG) and results in absence of GPUT activity and accumulation of galactose-1-phosphate (G-1-P) in erythrocytes. Classic galactosemia is characterized by failure to thrive, vomiting, liver disease, cataracts, and developmental delay. Useful for: Monitoring dietary therapy for classic galactosemia (total GPUT deficiency), galactosemia-Duarte (GD) patients, or rarely, patients with UDP galactose-4-epimerase deficiency. Interpretation: The reference values provided are for nongalactosemics and for galactosemic patients on a galactose-restricted diet. The goal of treatment of a galactosemic patient is to have G-1-P levels as low as possible, but no higher than 125 mcg/g of hemoglobin. Cautions: Not a screening test for galactosemia

Ultraviolet, Enzymatic This assay is a quantitative measure of the galactose-1-phosphate and is useful for monitoring the dietary management of galactosemics. This assay should not be used for the diagnosis of galactosemia.