Test Code MISC2MAYOGALTP Galactose-1-Phosphate Uridyltransferase Biochemical Phenotyping, Erythrocytes
Reporting Name
Gal-1-Phos Urdyltrns Phenotype,RBCUseful For
Determining the biochemical phenotype for galactosemia when enzymatic and molecular results are incongruent
Additional Tests
Test ID | Reporting Name | Available Separately | Always Performed |
---|---|---|---|
GALT | Gal-1-P Uridyltransferase, RBC | Yes | Yes |
Testing Algorithm
A quantitative galactose-1-phosphate uridyltransferase GALT) level is used in addition to the isoelectric focusing for accurate interpretation. If recent GALT test results are not provided, GALT will be automatically performed at an additional charge. However, if previous GALT results are provided, GALT testing will be cancelled and not charged.
See Galactosemia Testing Algorithm in Special Instructions.
Performing Laboratory

Specimen Type
Whole Blood EDTAAdvisory Information
GCT / Galactosemia Reflex, Blood is the preferred test to evaluate for possible diagnosis of galactosemia, routine carrier screening, and follow-up of abnormal newborn screening results.
For monitoring of dietary compliance, order GAL1P / Galactose-1-Phosphate (Gal-1-P), Erythrocytes.
Necessary Information
Patient's age is required.
A quantitative galactose-1-phosphate uridyltransferase level (GALT / Galactose-1-Phosphate Uridyltransferase, Blood) is required for accurate interpretation.
Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.
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: Lavender top (EDTA)
Specimen Volume: 3 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 |
Special Instructions
Reference Values
An interpretative report will be provided.
Day(s) and Time(s) Performed
Thursday; 9 a.m.
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
82664
82775
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
GALTP | Gal-1-Phos Urdyltrns Phenotype,RBC | 33780-8 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
80341 | Gal-1-Phos Urdyltrns Phenotype,RBC | 33780-8 |
34524 | Reviewed By | 18771-6 |
Reject Due To
Gross hemolysis | Reject |
Method Name
GALTP: Isoelectric Focusing
GALT: Enzyme Reaction followed by Liquid Chromatography-Tandem Mass
Spectrometry (LC-MS/MS)
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. Biochemical Genetics Patient Information (T602) is recommended, see Special Instructions.
3. If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen.