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Test Code RBC Enz Red Blood Cell (RBC) Enzyme Evaluation

Reporting Name

RBC Enzyme Evaluation

Useful For

Identifying defects of red cell enzyme metabolism

 

Evaluating patients with hemolytic anemia


Specimen Required


Container/Tube: Yellow top (ACD solution B)

Specimen Volume: 12 mL

Collection Instructions: Do not transfer blood to other containers.


Specimen Type

Whole Blood ACD-B

Specimen Minimum Volume

5 mL

Specimen Stability Information

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

Day(s) and Time(s) Performed

Monday through Friday; Varies

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

EEEV: Consultative Interpretation

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

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)

Reference Values

Definitive results and an interpretive report will be provided.

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

Reflex Tests

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

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

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

NA

 

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.

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)