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Test Code GPI1 Glucose Phosphate Isomerase Enzyme Activity, Blood

Reporting Name

Glucose Phosphate Isomerase, B

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

The evaluation of individuals with Coombs-negative chronic hemolysis

Method Name

Kinetic Spectrophotometry (KS)


Specimen Required


Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Lavender top (EDTA)

Specimen Volume: 6 mL

Collection Instructions: Send whole blood in original tube. Do not transfer blood to other containers.


Specimen Type

Whole Blood ACD-B

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD-B Refrigerated 20 days

Reject Due To

Gross Hemolysis Reject

Reference Values

≥12 months: 40.0-58.0 U/g Hb

Reference values have not been established for patients who are younger than 12 months of age.

Interpretation

Most clinically significant hemolytic anemias due to glucose phosphate isomerase (GPI) deficiency are associated with activity levels under 30% of mean normal; however, some clinically affected patients can have higher activity due to reticulocytosis. Heterozygotes usually show 40% to 60% of mean normal activity and are hematologically normal.

 

Increased GPI activity is variably seen when young red blood cells are being produced in response to the anemia (reticulocytosis) or in newborns.

Day(s) Performed

Tuesday, Thursday

Report Available

1 to 6 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

84087

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GPI1 Glucose Phosphate Isomerase, B 44050-3

 

Result ID Test Result Name Result LOINC Value
GPICL Glucose Phosphate Isomerase, B 44050-3

Forms

If not ordering electronically, complete, print, and send a Benign Hematology Test Request (T755) with the specimen.