Galactose-1-Phosphate Uridyltransferase, Blood

Alphabetical Test listing

Galactose-1-Phosphate Uridyltransferase, Blood-994

Galactose-1-Phosphate Uridyltransferase, Blood
G-1-PU (Galactose-1-Phosphate Uridyltransferase)
Galactose-1-Phosphate Uridyltransferase (GALT)
Galactosemia Enzyme
Classical Galactosemia

Diagnosis of galactose-1-phosphate uridyltransferase deficiency, the most common cause of galactosemia

Confirmation of abnormal state newborn screening results


This assay is not appropriate for monitoring dietary compliance. If dietary monitoring is needed, order GAL1P / Galactose-1-Phosphate, Erythrocytes.

This test is for galactose-1-phosphate uridyltransferase (GALT) enzyme testing only. The preferred test to evaluate for possible diagnosis of galactosemia, routine carrier screening, and follow-up of abnormal newborn screening results is GCT / Galactosemia Reflex, Blood.

This assay will not detect galactokinase (GALK) deficiency or uridine diphosphate-galactose 4' epimerase (GALE) deficiency.



The results of testing performed in erythrocytes, including analysis of enzymes, biochemical phenotyping, or galactose-1-phosphate are invalid following a transfusion. Patients should wait 3 to 4 months post transfusion before collecting whole blood for galactose-1-phosphate uridyltransferase testing.

EDTA whole blood
5 mL
2 mL

Immediately following collection, mix sample thoroughly by gently inverting 8 - 10, times to prevent clotting

Sodium heparin (Na hep) whole blood
ACD whole blood

Submit entire specimen


Refrigerated (preferred) - 28 days

Ambient - 14 days


Processed RBC: 2 months

Gross hemolysis

Mayo Clinic Laboratories (GALT): R-NX
Mo, We, Fr
3 - 6 days

Enzyme Reaction followed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)


≥ 24.5 nmol/h/mg of hemoglobin


Galactose-1-phosphate uridyltransferase (GALT) deficiency is the most common cause of galactosemia and requires lifelong restriction of dietary galactose.

Classic galactosemia can be diagnosed by analysis of GALT enzyme.

This test provides enzymatic testing for the diagnosis of GALT deficiency.

For more information see Galactosemia Testing Algorithm.