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Test ID MPO Myeloperoxidase Antibodies, IgG, Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Forms

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

Secondary ID

80389

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

Method Name

Multiplex Flow Immunoassay

Reporting Name

Myeloperoxidase Ab, S

Specimen Type

Serum

Specimen Minimum Volume

0.35 mL

Specimen Stability Information

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

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.

Reference Values

<0.4 U (negative)

0.4-0.9 U (equivocal)

≥1.0 U (positive)

Reference values apply to all ages.

Cautions

Since it is not possible to distinguish between microscopic polyangiitis (MPA) and other causes of progressive renal failure or systemic illness (eg, Wegener granulomatosis, lupus nephritis, Goodpasture syndrome), this test should be employed in conjunction with other diagnostic tests in the initial evaluation of such patients. The recommended test in this setting is VASC / Antineutrophil Cytoplasmic Antibodies Vasculitis Panel, Serum, which includes myeloperoxidase (MPO) antibodies, proteinase 3 (PR3) antibodies and, if indicated, antineutrophil cytoplasmic antibodies (ANCA). The test for ANCA identifies 2 types of antibodies-cytoplasmic (cANCA), which are specific for PR3 and perinuclear (pANCA), which are specific for MPO.

 

The presence of MPO is quite specific for MPA (diagnostic specificity approaches 95%); but, it is recommended that positive results obtained by EIA be confirmed by another testing method. This is best accomplished by testing for pANCA, which confirms the positive MPO result and increases the diagnostic specificity for MPA to 97%.(3) Nevertheless, positive results for MPO have been reported in patients with systemic lupus erythematosus, Goodpasture syndrome, and Churg-Strauss syndrome. Therefore, clinicians must rule out these diagnoses to maximize the specificity and positive predictive value of the MPO test result.

 

While sequential measurements of MPO may be used to follow treatment response or to monitor disease activity in patients with MPA, results should not be exclusively relied upon to assess response to treatment or disease activity.

Day(s) Performed

Monday through Saturday

Report Available

1 to 4 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

83516

NY State Approved

Yes