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Test Code GAL1P Galactose 1 Phosphate

Important Note

Test requires special processing.  Call Biochemical Genetics (987-2216) or Chemistry (987-2565) when collected.  If not available, call Drs. Rhona Jack (987-2569), Anna Scott (987-8603), or Jane Dickerson (987-8066). SCH Laboratory is permitted to draw blood on adults for this test.

Clinical System Name

Galactose 1 Phosphate




Used to monitor treatment of known Galactosemia patients.

Sample Requirements

Specimen: Whole Blood

Container(s):  Dark Green/Sodium Heparin Tube, Yellow/ACD A or B

Preferred Vol: 2.0 mL

Minimum Vol: 1.0 mL


Note:  Do NOT use gel separator tubes.


Processing Instructions

Reject due to:

Spin: N


Temp: RT

Special instructions:  Notify Biochemical Genetics (987-2216)  immediately so that cells can be washed before storing at -70 C. If not available, follow "Weekend Processing" instructions below. Blood collection on adults is permitted.

Weekend Processing: Call Chemistry West (987-2565). Procedure can be found in RBC enzyme section.


Off-site collection: Special processing required. Call biochemical genetics prior to collection with questions about processing. Samples received from outside labs should be frozen washed cells.  Store cells at -70 C (although -20 C is acceptable for short term transport). Cells must not thaw during transport.


Specimen Type Temperature Time
whole blood Room temp

≤1 hr after collection

whole blood Refrigerated < 1 hr after collection



STAT Performed TAT
N Weekly 7 days


Contact the Biochemical Genetics Lab for requests outside of stated availability (206)987-2216.

Performing Laboratory

Seattle Children's Laboratory    


Department:  Biochemical Genetics

Phone Number: 206-987-2216


Reference Range



Preferred Range for Patients with Galactosemia

4 mg/dL



Method: Fluorometric

Analytical Volume:


CPT Codes



Biochemical Genetics Requisition


On the requisition include clinical information needed for appropriate interpretation. (Age, gender, drug therapy and family history)

Clinical Utility

Galactosemia is an inherited disorder of galactose metabolism. Individuals with galactosemia are unable to break down galactose, a sugar found primarily in dairy products and some vegetables and legumes. Galactosemia is caused by a deficiency in the enzyme galactose-1-phosphate uridyltransferase, and individuals with galactosemia have mutations in the GALT gene. They also have elevated galactose-1-phosphate, a metabolite of galactose metabolism that is used for dietary monitoring in affected patients. Patients with defects in the GALE gene (UDP-galactose-4-epimerase deficiency) would also have elevated galactose-1-phosphate. patients with defects in the GALK  gene (galactokinase deficiency) would have normal galactose 1-phosphate, but elevated galactose.