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Test Code EEEVP Red Blood Cell (RBC) Enzyme Evaluation

Performing Laboratory

Mayo Medical Laboratories in Rochester

Reporting Name

RBC Enzyme Evaluation

Specimen Type

Whole Blood ACD-B


Specimen Required


Container/Tube: Yellow top (ACD solution B)

Specimen Volume: 12 mL

Collection Instructions: Do not transfer blood to other containers.


Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

NA

 

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood ACD-B Refrigerated 8 days

Specimen Minimum Volume

5 mL

Day(s) and Time(s) Performed

Monday through Friday; Varies

Specimen Retention Time

14 days

Analytic Time

2-10 days (not reported Saturday or Sunday)

Reference Values

Definitive results and an interpretive report will be provided.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
GLTI Glutathione, B No No
RBCE Reflexed RBC Enzymes No No

Useful For

Identifying defects of red cell enzyme metabolism

 

Evaluating patients with hemolytic anemia

Testing Algorithm

This is a consultative evaluation in which the case will be evaluated at Mayo Medical Laboratories, the appropriate tests performed at an additional charge, and the results interpreted.

Note: RBCE / Reflexed RBC Enzymes, Blood includes: adenylate kinase, phosphofructokinase, phosphoglycerate kinase, triosephosphate isomerase, and pyrimidine 5'nucleotidase.

Method Name

EEEV: Consultative Interpretation

G6PD, GPI, PK, GLTI, HEXK, RBCE: Kinetic Spectrophotometry (KS)

Test Classification

See Individual Test IDs

CPT Code Information

82955-G-6-PD

84087-Glucose phosphate isomerase

84220-Pyruvate kinase

82657-Hexokinase

82978-Glutathione (if appropriate)

83915-RBC Enzymes (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
EEEVP RBC Enzyme Evaluation In Process

 

Result ID Test Result Name Result LOINC Value
21065 Erythrocyte Enzyme Interpretation 59466-3
G6PD_ G-6-PD, QN, RBC 32546-4
GPI_ Glucose Phosphate Isomerase, B 44050-3
HEXK_ Hexokinase, B 49216-5
PK_ Pyruvate Kinase, RBC 32552-2

Clinical Information

All enzyme defects, including erythrocyte enzyme errors, are inherited; some are sex-linked and located on the X chromosome. Some family members have no hematologic abnormalities, while others have a hemolytic anemia. For a number of RBC enzyme defects (eg, deficiencies of hexokinase, glucose phosphate isomerase, pyruvate kinase), the sole clinical manifestation is hemolytic anemia. Glucose-6-phosphate dehydrogenase deficiency is the most common metabolic error of the red cell and presents with acute hemolytic anemia in response to oxidant stress (eg, drugs, acute infections, fava bean ingestion).

 

This is a consultative evaluation looking at red cell enzyme defects as the cause for early red cell destruction.

Interpretation

A hematopathologist expert in these disorders evaluates the case, appropriate tests are performed, and an interpretive report is issued.

Cautions

No significant cautionary statements

Clinical Reference

Beutler E: Glucose-6-phosphate dehydrogenase deficiency and other enzyme abnormalities. In Hematology. Fifth edition. Edited by E Beutler, MA Lichtmann, BS Coller, TJ Kipps. New York, McGraw-Hill Book Company, 1995, pp 564-581

Method Description

Erythrocyte Enzyme Interpretation:

A hematopathologist who is an expert in these disorders evaluates the case, appropriate tests are performed and an interpretive report is issued.

 

Glucose-6-Phosphate Dehydrogenase (G6PD):

G6PD in a hemolysate catalyzes the oxidation of glucose-6-phosphate to 6-phosphogluconate. Concomitantly, nicotinamide adenine dinucleotide phosphate (NADP) is changed to its reduced form (nicotinamide adenine dinucleotide phosphate-oxidase: NADPH), a reaction measured spectrophotometrically.(Beutler E: Red Cell Metabolism: A Manual of Biochemical Methods. Third edition. New York, Grune and Stratton, 1984, pp 68-71)

 

Pyruvate Kinase:

A red cell hemolysate is incubated with adenosine diphosphate and phosphoenolpyruvate. The amount of pyruvate formed is quantitated by adding lactic dehydrogenase and reduced nicotinamide adenine di-nucleotide and measuring the rate of decrease in absorbance at 340 nm.(Beutler E: Red Cell Metabolism: A Manual of Biochemical Methods. Third edition. New York, Grune and Stratton, 1984, pp 68-71)

 

Glucose Phosphate Isomerase:

Washed erythrocytes are hemolyzed and the hemolysate is mixed with glucose, adenosine triphosphate (ATP), glucose-6-phosphate dehydrogenase, and nicotinamide adenine dinucleotide phosphate (NADP). The reduction of NADP is measured spectrophotometrically and is proportional to the enzymatic conversion of ATP and glucose to glucose-6-phosphate.(Beutler E: Red Cell Metabolism: A Manual of Biochemical Methods. Third edition. New York, Grune and Stratton, 1984, pp 40-42)

 

Hexokinase:

Hexokinase (in the presence of magnesium) catalyzes the reaction of ATP and glucose to G-6-P and ADP. In this assay the formation of glucose-6-phosphate (G-6-P) is measured by linking its further oxidation to 6-phosphogluconate (6-PG) to the reduction of NADP through the glucose-6-phosphate dehydrogenase (G-6-PD) reaction. The increase in absorbance which occurs as NADP+ is reduced is measured at 340 nm.(Beutler E: Red cell metabolism: A Manual of Biochemical Methods. Third edition. Grune and Stratton, New York, 1984, pp 38-40)

 

Glutathione:

Virtually all of the nonprotein sulfhydryl of red cells is in the form of reduced glutathione (GSH). 5,5'-dithiobis (2-nitrobenzoic acid) is a disulfide compound which is readily reduced by sulfhydryl compounds, forming a highly colored yellow anion. The absorbance of this resultant yellow substance is measured by 412 nm and compared to that of a known standard.(Beutler E: Red cell metabolism. In A Manual of Biochemical Methods, Second edition, Grune and Stratton, 1984)

Profile Information

Test ID Reporting Name Available Separately Always Performed
EEEV Erythrocyte Enzyme Interpretation No Yes
G6PD G-6-PD, QN, RBC Yes Yes
PK Pyruvate Kinase, RBC Yes Yes
GPI Glucose Phosphate Isomerase, B Yes Yes
HEXK Hexokinase, B No Yes

Forms

If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/benign-hematology-test-request-form.pdf)