The Anti-Neutrophil Cytoplasmic Antibody (ANCA) PR3 test detects proteinase 3 (PR3) antibodies, which are strongly associated with granulomatosis with polyangiitis (GPA, formerly Wegener’s granulomatosis). This test helps diagnose ANCA-associated vasculitis (AAV), a group of autoimmune diseases that cause inflammation of small blood vessels.
✅ Diagnose Granulomatosis with Polyangiitis (GPA, Wegener’s granulomatosis)
✅ Differentiate types of ANCA-associated vasculitis (GPA vs. MPA vs. EGPA)
✅ Monitor disease activity and treatment response
| Result | Interpretation |
|---|---|
| Negative | No significant PR3 antibodies detected (low likelihood of GPA) |
| Low Positive | May indicate mild inflammation or early disease, further evaluation needed |
| High Positive | Suggests granulomatosis with polyangiitis (GPA) or active vasculitis |
🔹 PR3-ANCA is strongly associated with GPA, but a negative test does not rule out disease.
🔹 Myeloperoxidase (MPO) ANCA is also tested to differentiate other types of vasculitis (MPA, EGPA).
| ANCA Type | Fluorescence Pattern | Associated Disease |
|---|---|---|
| PR3-ANCA (c-ANCA) | Cytoplasmic (c-ANCA) | Granulomatosis with Polyangiitis (GPA) |
| MPO-ANCA (p-ANCA) | Perinuclear (p-ANCA) | Microscopic Polyangiitis (MPA), Eosinophilic Granulomatosis with Polyangiitis (EGPA/Churg-Strauss Syndrome) |
| Atypical ANCA | Irregular staining | Seen in inflammatory bowel disease (IBD), infections |
🔹 Persistent sinusitis or nasal congestion
🔹 Cough, shortness of breath, or lung nodules
🔹 Kidney involvement (glomerulonephritis) → Blood in urine, kidney failure
🔹 Joint pain, skin ulcers, or eye inflammation
🔹 Nerve involvement → Weakness, tingling in limbs
✔ MPO-ANCA (p-ANCA) → Helps differentiate MPA vs. GPA
✔ Inflammatory Markers (ESR, CRP) → Assess disease activity
✔ Kidney Function Tests (Creatinine, Urinalysis) → Check for vasculitis-related kidney damage
✔ Chest X-ray or CT Scan → Look for lung involvement
✔ Tissue Biopsy (Kidney, Lung, or Nasal) → Confirms vasculitis diagnosis
🔹 Consult a rheumatologist or nephrologist for further evaluation.
🔹 Start immunosuppressive treatment (steroids, rituximab, cyclophosphamide) if active vasculitis is present.
🔹 Monitor regularly for disease flares or organ involvement.