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Test ID: MPO Myeloperoxidase Antibodies, IgG, Serum

Reporting Name

Myeloperoxidase Ab, S

Useful For

Evaluating patients suspected of having immune-mediated vasculitis, especially microscopic polyangiitis (MPA), when used in conjunction with other autoantibody tests (see Cautions)


May be useful to follow treatment response or to monitor disease activity in patients with MPA

Clinical Information

Myeloperoxidase (MPO) enzyme is found in neutrophil primary granules and monocyte lysosomes. MPO catalyzes the conversion of hydrogen peroxide to hypochlorite and hypochlorous acid. MPO is encoded by a single gene that undergoes posttranslational modification to produce the active enzyme found in leukocytes.


Autoantibodies to MPO (MPO antineutrophil cytoplasmic antibodies: ANCA) occur in several diseases and may be involved in the pathogenesis of vascular inflammation in patients with microscopic polyangiitis (MPA).(1,2) Patients with MPA often develop MPO ANCA and may present with azotemia secondary to glomerulonephritis (pauci-immune necrotizing glomerulonephritis). MPO ANCA are not specific for MPA, and also may be detected in patients with systemic lupus erythematosus with or without lupus nephritis, Goodpasture syndrome and Churg-Strauss syndrome. Lupus nephritis and Goodpasture syndrome, as well as Wegener granulomatosis may present with azotemia and progressive renal failure. It is not possible to distinguish among these diseases on the basis of clinical signs and symptoms; autoantibody testing may be helpful.


A positive result has a high predictive value for microscopic polyangiitis (MPA) in patients with negative test results for systemic lupus erythematosus (antinuclear antibodies) and Goodpasture syndrome (glomerular basement membrane antibody). A negative result significantly diminishes the likelihood that a patient has MPA.(3)


While myeloperoxidase levels often decline following successful treatment of MPA, specific guidelines for this clinical purpose are not available.

Report Available

1 to 4 days

Day(s) Performed

Monday through Saturday

Clinical Reference

1. Falk RJ, Jennette JC: Anti-neutrophil cytoplasmic autoantibodies with specificity for myeloperoxidase in patients with systemic vasculitis and idiopathic necrotizing and crescentic glomerulonephritis. N Engl J Med 1988 Jun 23;318(25):1651-1657

2. Stone JH, Hellman DB: Small and medium-vessel vasculitis. In Clinical Immunology Principles and Practice. Third edition. Edited by RR Rich, TA Fleisher, WT Shearer, et al. Mosby/Elsevier, 2007, pp 859-884

3. Russell KA, Wiegert E, Schroeder DR, et al: Detection of antineutrophil cytoplasmic antibodies under actual clinical testing conditions. Clin Immunol 2002 May;103(2):196-203

Method Name

Multiplex Flow Immunoassay

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL

Specimen Minimum Volume

0.35 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Reference Values

<0.4 U (negative)

0.4-0.9 U (equivocal)

≥1.0 U (positive)

Reference values apply to all ages.

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
MPO Myeloperoxidase Ab, S 48404-8


Result ID Test Result Name Result LOINC Value
MPO Myeloperoxidase Ab, S 48404-8


If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.

Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-Behavioral, mml-Cerebrovascular, mml-Epilepsy, mml-Headache, mml-Demyelinating-Diseases, mml-Neuroimmunology, mml-Neuromuscular, mml-Autonomic, mml-Pediatric, mml-Spinal-Cord, mml-Neuro-ophthalmology