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Test Code GALK Galactokinase, Blood

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Galactokinase, B

Specimen Type

Whole Blood EDTA


Ordering Guidance


This test is for diagnosis of galactokinase (GALK) deficiency and does not detect either galactose-1-phosphate uridyltransferase (GALT) deficiency (the most common cause of galactosemia), uridine diphosphate-galactose 4' epimerase (GALE) deficiency, or galactose mutarotase (GALM) deficiency. In most cases, GALT deficiency should be ruled out prior to evaluating for GALK deficiency.

-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.

-To evaluate GALT deficiency only, order GALT / Galactose-1-Phosphate Uridyltransferase, Blood

-To evaluate for GALE deficiency only, order GALE / UDP-Galactose 4' Epimerase (GALE), Blood

-To evaluate for GALM deficiency, order GALP / Galactose, Plasma and molecular analysis of the GALM gene.

 

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



Necessary Information


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. For a list of tests that can be ordered together see Galactosemia-Related Test List.

 

Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium or lithium heparin) or yellow top (ACD)

Specimen Volume: 4 mL


Reject Due To

Gross hemolysis Reject

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated (preferred) 10 days
  Ambient  72 hours

Specimen Minimum Volume

2 mL

Day(s) Performed

Monday

Specimen Retention Time

2 months

Report Available

5 to 11 days

Reference Values

≥0.7 nmol/h/mg of hemoglobin

Useful For

Diagnosis of galactokinase deficiency

 

Evaluation of children with unexplained bilateral congenital or juvenile onset cataracts

Testing Algorithm

For more information see Galactosemia Testing Algorithm.

CPT Code Information

82759

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GALK Galactokinase, B 81143-0

 

Result ID Test Result Name Result LOINC Value
38005 Galactokinase, B 81143-0
38007 Interpretation (GALK) 59462-2
38006 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:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602) is recommended.

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

Genetics Test Information

Enzymatic testing for the diagnosis of galactokinase deficiency.