MPO and PR3 antibody tests
Quick answer: These blood tests measure antibodies against two specific neutrophil proteins, myeloperoxidase (MPO) and proteinase 3 (PR3). Doctors usually order them with or after an ANCA test to help diagnose and follow types of vasculitis.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
How the test is done
- 1A nurse checks your name and the tests requested
- 2A tourniquet is placed and a vein in your arm is chosen
- 3A needle draws a tube of blood
- 4The lab measures MPO and PR3 antibody levels by an immunoassay
What your results can mean
Reading your report
Ranges and cut-offs differ between labs and methods, so discuss your result with your doctor.
If the result is outside the usual range
A raised PR3 level can be seen with granulomatosis with polyangiitis, and a raised MPO level with microscopic polyangiitis, eosinophilic granulomatosis or some kidney inflammation. Levels can fall with treatment and rise again before a flare.
Who usually has this test
People with a positive ANCA, or with kidney, lung or sinus symptoms that suggest vasculitis, and people being followed for known vasculitis.
Risks and aftercare
A small bruise is possible; you can go back to normal activities straight away.
Names and options
Also called: anti-MPO, anti-PR3, myeloperoxidase antibody, proteinase 3 antibody
Options
- Anti-MPO
- Anti-PR3
Listed by the hospital as
- ANTI MPO, SERUM
- ANTI PR3
Questions about this test
Why test MPO and PR3 if ANCA is already done?
The ANCA stain shows a pattern, while MPO and PR3 tests show which target protein the antibodies attack. Together they are more specific for vasculitis than either test alone.
Can MPO or PR3 tests be used to follow treatment?
Doctors sometimes repeat them during treatment. A falling level is reassuring, but levels do not always match how active the disease is, so symptoms and urine and kidney tests matter too.
Can I have vasculitis with negative MPO and PR3?
Yes. A small number of people with vasculitis test negative. A tissue biopsy may be needed to confirm the diagnosis.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
Reception
Waiting area
IVF lab
This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.