Evaluating patients suspected of having immune-mediated
May be useful to follow treatment response or to monitor
Multiplex Flow Immunoassay
ANCA (Antineutrophil Cytoplasmic Antibodies)
Anti-Myeloperoxidase Antibodies
Antibodies to Myeloperoxidase
Anticytoplasmic Autoantibodies
Antineutrophil Cytoplasmic Antibodies (ACPA)
Autoantibodies to Myeloperoxidase
Autoantibodies to Proteinase 3
Cytoplasmic Neutrophil Antibodies
Myeloperoxidase Antibodies (MPO)
Neutrophil Cytoplasmic Antibodies
Wegener's Granulomatosis
Perinuclear Antineutrophil Cytoplasmic Antibody (pANCA)
Serum
Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 0.5 mL
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.
0.35 mL
Gross hemolysis | Reject |
Gross lipemia | Reject |
Gross icterus | OK |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 21 days | |
Frozen | 21 days |
Evaluating patients suspected of having immune-mediated
May be useful to follow treatment response or to monitor
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.
<0.4 U (negative)
0.4-0.9 U (equivocal)
> or =1.0 U (positive)
Reference values apply to all ages.
A positive result has a high predictive value for microscopic polyangiitis (MPA) in patients
While myeloperoxidase levels often decline following successful treatment
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.
1. Falk RJ, Jennette JC: Anti-neutrophil cytoplasmic autoantibodies with specificity for myeloperoxidase in patients with systemic vasculitis and idiopathic necrotizing and crescentic glomerulonephritis.
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
Myeloperoxidase (MPO) antigen is covalently coupled to polystyrene microspheres that are impregnated with fluorescent dyes to create a unique fluorescent signature. MPO antibodies, if present in diluted serum, bind to the MPO antigen on the microspheres. The microspheres are washed to remove extraneous serum proteins. Phycoerythrin (PE)-conjugated antihuman IgG antibody is then added to detect IgG anti-MPO bound to the microspheres. The microspheres are washed to remove unbound conjugate, and bound conjugate is detected by laser photometry. A primary laser reveals the fluorescent signature of each microsphere to distinguish it from microspheres that are labeled with other antigens. A secondary laser reveals the level of PE fluorescence associated with each microsphere. Results are calculated by comparing the median fluorescence response for MPO microspheres to a 4-point calibration curve.(Package insert: Bio-Plex 2200 Vasculitis. Bio-Rad Laboratories, Hercules, CA 2012)
Monday through Saturday
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.
83516
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
MPO | Myeloperoxidase Ab, S | 48404-8 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
MPO | Myeloperoxidase Ab, S | 48404-8 |