Order Code MISMA - GOKEY GCT Galactosemia Reflex, Blood
Additional Codes
Mayo Test ID: GCT
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
Specimen Type
Whole Blood EDTASpecimen Required
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 5 mL
Additional Information: Patient's age is required.
Specimen Minimum Volume
2 mL
Specimen Stability Information
Specimen Type | Temperature | Time |
---|---|---|
Whole Blood EDTA | Refrigerated (preferred) | 28 days |
Ambient | 14 days |
Reject Due To
Hemolysis |
Mild OK; Gross reject |
Lipemia |
NA |
Icterus |
NA |
Other |
NA |
Reference Values
≥24.5 nmol/h/mg of hemoglobin
Performing Laboratory

Day(s) and Time(s) Performed
Monday, Wednesday, Friday; 7 a.m. set up (specimen must arrive the day prior)
Method Name
Enzyme Reaction Followed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
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
Galactose-1-Phosphate Uridyltransferase (GALT), Blood
82775
Galactosemia Gene Analysis (14-Mutation Panel)
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
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
GCT | Galactosemia Reflex, B | In Process |
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 |
Special Instructions
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, GAL14 / Galactosemia Gene Analysis (14-Mutation Panel) will be performed at an additional charge.
See Galactosemia Testing Algorithm in Special Instructions.
Reflex Tests
Test ID | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
GAL14 | Galactosemia Gene Analysis | Yes | No |
Forms
1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.
2. If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.