Sign in →

Test ID: GPI Glucose Phosphate Isomerase, Erythrocytes

Reporting Name

Glucose Phosphate Isomerase, B

Useful For

A second-order test in the evaluation of individuals with chronic hemolysis

Clinical Information

Erythrocyte glucose phosphate isomerase (GPI) deficiency has been reported as a cause of chronic hemolysis in numerous cases. Inheritance is autosomal recessive. Hemolytic disease of the newborn is a common presenting manifestation of GPI deficiency.


Glucose phosphate isomerase (GPI) deficiency causes a moderately severe anemia. GPI values can be 25% of normal.


Increased GPI activity may be seen when young red blood cells are being produced in response to the anemia (reticulocytosis) or in the case of a newborn.

Analytic Time

3 days

Day(s) and Time(s) Performed

Monday through Friday

Clinical Reference

Fairbanks VF, Klee GG: Biochemical aspects of hematology. In Tietz Textbook of Clinical Chemistry. Third Edition. Edited by CA Burtis, ER Ashwood, Philadelphia, WB Saunders Company, 1999, pp 1642-1646

Method Name

Kinetic Spectrophotometry (KS)

Specimen Type

Whole Blood ACD-B

Specimen Required


Preferred: Yellow top (ACD solution B)

Acceptable: EDTA

Specimen Volume: 6 mL

Collection Instructions: Do not transfer blood to other containers.

Specimen Minimum Volume

1 mL

Specimen Stability Information

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

Reference Values

≥12 months: 39.3-57.7 U/g Hb

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

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


LOINC Code Information

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


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


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

Mayo Clinic Laboratories | Endocrinology Catalog Additional Information: