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Order Code METR1 Cytochrome b5 Reductase Enzyme Activity, Blood


Necessary Information


 



Specimen Required


Collection Container/Tube:

Preferred: Yellow top (ACD)

Acceptable: Lavender top (EDTA)

Specimen Volume: 6 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.


Useful For

Evaluation of patients with cyanosis

 

Confirming cases of suspected cytochrome b5 reductase (methemoglobin reductase) deficiency

 

Functional studies in families with cytochrome b5 reductase deficiency

Method Name

Kinetic Spectrophotometry (KS)

Reporting Name

Cytochrome b5 Reductase, B

Specimen Type

Whole Blood ACD-B

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD-B Refrigerated 18 days

Reject Due To

Gross hemolysis Reject

Reference Values

≥12 months of age: 7.8-13.1 U/g Hb

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

Method Description

Cytochrome b5 reductase (methemoglobin reductase) catalyzes the 1,4-dihydronicotinamide adenine dinucleotide (NADH)-linked reduction of several substrates, including ferricyanide. The activity at 37° C is measured spectrophotometrically by measuring the oxidation of NADH to NAD(+) at 340 nm on an automated chemistry analyzer.(Fairbanks VF, Klee GG. Biochemical aspects of hematology. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. WB Saunders Company. 1999:1647-1648; van Solinge WW, van Wijk. Enzymes of the red blood cell. In: Rifai N, Horvath AR, Wittwer CT. eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:chap 30)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Day(s) Performed

Performed weekly

CPT Code Information

82657

Forms

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