Test Code GCT Galactosemia Reflex, Blood
Reporting Name
Galactosemia Reflex, BUseful For
Preferred test for diagnosis, carrier detection, and determination of genotype of galactose-1-phosphate uridyltransferase deficiency, the most common cause of galactosemia
Differentiating Duarte variant galactosemia from classic galactosemia
Confirming results of newborn screening programs
Reflex Tests
Test ID | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
GAL14 | Galactosemia Gene Analysis | Yes | No |
Testing Algorithm
Testing begins with galactose-1-phosphate uridyltransferase (GALT) enzyme analysis. If GALT is greater than or equal to 24.5 nmol/h/mg of hemoglobin, testing is complete. No molecular test will be performed. If GALT is less than 24.5 nmol/h/mg of hemoglobin, galactosemia gene analysis) will be performed at an additional charge.
See Galactosemia Testing Algorithm in Special Instructions.
Method Name
Enzyme Reaction followed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Performing Laboratory

Specimen Type
Whole Blood EDTAAdvisory Information
This test is appropriate for the diagnosis of and routine carrier screening for galactose-1-phosphate uridyltransferase (GALT) deficiency.
This assay is not appropriate for monitoring dietary compliance. For dietary monitoring, order GAL1P / Galactose-1-Phosphate (Gal-1-P), Erythrocytes.
Necessary Information
Patient's age is required.
Specimen Required
Multiple whole blood tests for galactosemia can be performed on 1 specimen. Prioritize order of testing when submitting specimens. See Galactosemia-Related Test List in Special Instructions for a list of tests that can be ordered together.
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 5 mL
Specimen Minimum Volume
2 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Whole Blood EDTA | Refrigerated (preferred) | 28 days | |
Ambient | 14 days |
Reject Due To
Gross hemolysis | Reject |
Special Instructions
Reference Values
≥24.5 nmol/h/mg of hemoglobin
Day(s) and Time(s) Performed
Monday, Wednesday, Friday; 7 a.m. set up (specimen must arrive the day prior)
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
82775
81401-GALT (galactose-1-phosphate uridylyltransferase) (eg, galactosemia), common variants (eg, Q188R, S135L, K285N, T138M, L195P, Y209C, IVS2-2A->G, P171S, del5kb, N314D, L218L/N314D, if appropriate
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
GCT | Galactosemia Reflex, B | 24082-0 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
8333 | Gal-1-P Uridyltransferase, RBC | 24082-0 |
2296 | Interpretation (GALT) | 59462-2 |
58115 | Reviewed By | 18771-6 |
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.