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Test Code GPI1 Glucose Phosphate Isomerase Enzyme Activity, Blood


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 aliquot.


Useful For

Evaluating individuals with Coombs-negative chronic hemolysis

Method Name

Kinetic Spectrophotometry (KS)

Reporting Name

Glucose Phosphate Isomerase, B

Specimen Type

Whole Blood ACD-B

Specimen Minimum Volume

1 mL

Specimen Stability Information

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

Reference Values

≥12 months: 40.0-58.0 U/g Hb

Reference values have not been established for patients younger than 12 months.

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. Heterozygous individuals usually show 40% to 60% of mean normal activity and are hematologically normal.

 

Variability of increased GPI activity is seen when young red blood cells are produced in response to anemia (reticulocytosis) or in newborns.

Clinical Reference

1. Manco L, Bento C, Victor BL, et al. Hereditary nonspherocytic hemolytic anemia caused by red cell glucose-6-phosphate isomerase (GPI) deficiency in two Portuguese patients: Clinical features and molecular study. Blood Cells Mol Dis. 2016;60:18-23

2. Mojzikova R, Koralkova P, Holub D, et al. Two novel mutations (p.(Ser160Pro) and p.(Arg472Cys)) causing glucose-6-phosphate isomerase deficiency are associated with erythroid dysplasia and inappropriately suppressed hepcidin. Blood Cells Mol Dis. 2018;69:23-29

3. Fairbanks VF, Klee GG. Biochemical aspects of hematology. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. WB Saunders Company; 1999:1642-1646

4. Koralkova P, van Solinge WW, van Wijk R. Rare hereditary red blood cell enzymopathies associated with hemolytic anemia-pathophysiology, clinical aspects and laboratory diagnosis. Int J Lab Hematol. 2014;36(3):388-397

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

Day(s) Performed

Tuesday, Thursday

Report Available

1 to 6 days

Forms

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