ANTI-PR3 ANTIBODIES - CANCA

The Anti-PR3 Antibodies (cANCA) Test is a specialized blood test that detects autoantibodies against Proteinase 3 (PR3), an enzyme found in neutrophils (a type of white blood cell). These antibodies are strongly associated with Cytoplasmic Anti-Neutrophil Cytoplasmic Antibodies (cANCA) and are an important diagnostic marker for ANCA-associated vasculitis (AAV), particularly Granulomatosis with Polyangiitis (GPA), formerly known as Wegener's Granulomatosis.

ANCA-associated vasculitis is a group of autoimmune disorders in which the immune system attacks small and medium-sized blood vessels, causing inflammation and tissue damage. This inflammation can affect multiple organs, including the nose, sinuses, lungs, kidneys, skin, eyes, and peripheral nerves. Without early diagnosis and treatment, the disease may lead to permanent organ damage and life-threatening complications.

The Anti-PR3 (cANCA) Test is considered one of the most specific laboratory tests for diagnosing Granulomatosis with Polyangiitis (GPA). It is frequently performed alongside the Anti-MPO (pANCA) Antibody Test, inflammatory markers, kidney function tests, imaging studies, and tissue biopsy to accurately diagnose and classify vasculitis.

Early identification of PR3 antibodies enables timely treatment with immunosuppressive medications, helping reduce disease activity, prevent relapses, and preserve organ function.

Benefits of the Test

• Detects Anti-Proteinase 3 (PR3) autoantibodies
• Supports diagnosis of Granulomatosis with Polyangiitis (GPA)
• Helps diagnose ANCA-associated vasculitis
• Assists in evaluating autoimmune small vessel vasculitis
• Supports treatment planning and disease monitoring
• Helps assess relapse risk in some patients
• Requires only a peripheral blood sample

Why Doctors Recommend This Test

Doctors may recommend this test if a patient has:

• Chronic sinus infections or nasal ulcers
• Persistent cough
• Coughing up blood (hemoptysis)
• Shortness of breath
• Blood in the urine (hematuria)
• Kidney dysfunction
• Persistent fever
• Unexplained weight loss
• Skin rash or purpura
• Suspected Granulomatosis with Polyangiitis or ANCA-associated vasculitis

Preparation Before Test

Sample Required

• Peripheral venous blood sample (Serum)

Preparation Guidelines

• No fasting is generally required.
• Continue medications unless instructed otherwise by your physician.
• Inform your healthcare provider about autoimmune diseases, recent infections, and current medications.
• Follow laboratory instructions before sample collection.

Reporting Time

Results are generally available within 3–7 working days, depending on laboratory methodology.

Who Should Take This Test?

This test is recommended for:

• Individuals with suspected Granulomatosis with Polyangiitis (GPA)
• Patients with unexplained vasculitis symptoms
• Individuals with chronic sinus, lung, or kidney inflammation
• Patients with suspected ANCA-associated vasculitis
• Individuals with abnormal kidney function due to autoimmune disease
• Patients referred by rheumatologists, nephrologists, pulmonologists, or immunologists

Clinical Significance

A positive Anti-PR3 (cANCA) antibody result may indicate:

• Granulomatosis with Polyangiitis (GPA)
• ANCA-Associated Vasculitis (AAV)
• Small Vessel Vasculitis
• Pauci-Immune Glomerulonephritis

Common symptoms associated with these conditions include:

• Persistent sinusitis
• Nosebleeds
• Nasal ulcers
• Chronic cough
• Coughing up blood
• Shortness of breath
• Blood in urine
• Kidney dysfunction
• Fatigue
• Fever
• Weight loss
• Joint pain
• Skin rashes

A positive Anti-PR3 antibody result strongly supports the diagnosis of Granulomatosis with Polyangiitis, but results should always be interpreted together with clinical findings, Anti-MPO (pANCA) testing, inflammatory markers, kidney function tests, imaging studies, and tissue biopsy when appropriate.