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Test Code MetHgbRed Methemoglobin Reductase, Blood

Reporting Name

Methemoglobin Reductase, B

Useful For

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


Functional studies in families with methemoglobin reductase (cytochrome b5 reductase) deficiency

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Whole Blood ACD-B

Specimen Required


Preferred: Yellow top (ACD)

Acceptable: Lavender top (EDTA)

Specimen Volume: 6 mL

Collection Instructions: Do not transfer blood to other containers.

Additional Information: Patient's age is required.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood ACD-B Refrigerated 22 days

Reference Values

≥12 months: 6.6-13.3 U/g Hb

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

Day(s) and Time(s) Performed

Tuesday, Friday

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
METR Methemoglobin Reductase, B 32703-1


Result ID Test Result Name Result LOINC Value
9322 Methemoglobin Reductase, B 32703-1

Method Description

Methemoglobin reductase (cytochrome b5 reductase) catalyzes the NADH-linked reduction of several substrates, including ferricyanide. The activity at 30° C is followed spectrophotometrically by measuring the oxidation of NADH at 340 nm.(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 1647-1648)

Reject Due To


Mild OK; Gross reject







Method Name

Kinetic Spectrophotometry (KS)