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HelpTest 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, BSpecimen Type
Whole Blood ACD-BSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole Blood ACD-B | Refrigerated | 20 days |
Reject Due To
| Gross hemolysis | Reject |
| Fully clotted | Reject |
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.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
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 daysForms
If not ordering electronically, complete, print, and send a Benign Hematology Test Request (T755) with the specimen.