ANCA by IFA Reflex Endpoint Titre Test – Detailed Guide

The ANCA (Anti-Neutrophil Cytoplasmic Antibody) by IFA Reflex Endpoint Titre Test is used to detect autoimmune vasculitis and other autoimmune diseases affecting blood vessels. The test identifies ANCAs using Indirect Immunofluorescence Assay (IFA) and determines the endpoint titre to measure the antibody concentration.

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Why is the ANCA Test Done?

✅ To Diagnose Autoimmune Vasculitis Conditions:

• Granulomatosis with Polyangiitis (GPA, formerly Wegener’s Disease)
• Microscopic Polyangiitis (MPA)
• Eosinophilic Granulomatosis with Polyangiitis (EGPA, formerly Churg-Strauss Syndrome)

✅ To Identify Symptoms of ANCA-Associated Vasculitis (AAV):

• Unexplained fever, weight loss, and fatigue
• Persistent sinusitis or nasal ulcers
• Coughing up blood (hemoptysis) or shortness of breath
• Kidney involvement (blood in urine, kidney failure symptoms)
• Skin rashes or ulcers

✅ To Differentiate Between ANCA Subtypes:

• c-ANCA (Cytoplasmic ANCA, associated with PR3 antibodies) – Suggests Granulomatosis with Polyangiitis (GPA)
• p-ANCA (Perinuclear ANCA, associated with MPO antibodies) – Suggests Microscopic Polyangiitis (MPA) or EGPA

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Test Procedure

🩸 Blood Sample Collection:

• A blood sample is drawn from a vein
• No fasting required
• Results typically available in 3–5 days

🧪 Test Process (IFA Reflex Method):

1. Screening Test (IFA ANCA) – Detects the presence of ANCAs
2. Reflex Endpoint Titre – If positive, dilution titers (1:40, 1:80, 1:160, etc.) determine the antibody concentration

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Understanding Test Results

🔹 Higher Endpoint Titre Values (≥1:160) Suggest Stronger Autoimmune Activity

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Next Steps If ANCA is Positive?

🔬 Further Tests May Be Needed:

• PR3 & MPO Antibody Test – Confirms the type of vasculitis
• Kidney Function Tests (Creatinine, Urinalysis) – Checks for kidney involvement
• Chest X-ray or CT Scan – If lung involvement is suspected
• Biopsy (Kidney, Lung, or Skin) – In severe cases to confirm vasculitis

✅ Treatment Depends on the Underlying Condition

• Immunosuppressants (Steroids, Cyclophosphamide, Rituximab) for vasculitis
• Kidney or lung disease management if organs are affected