Anti Neutrophilic Cytoplasmic Antibody - Titers

The ANCA titer test detects antineutrophil cytoplasmic antibodies in blood to help diagnose and monitor small-vessel vasculitis (for example granulomatosis with polyangiitis and microscopic polyangiitis) and some autoimmune conditions. Results are reported as titers and patterns; higher or rising titers can indicate active disease or relapse, while falling titers suggest response to treatment. It supports clinical and other laboratory findings.

ANCAs are characteristically positive in ANCA-associated vasculitides: granulomatosis with polyangiitis (c-ANCA/PR3), microscopic polyangiitis (p-ANCA/MPO), and eosinophilic granulomatosis with polyangiitis (p-ANCA/MPO). They may also appear in drug-induced vasculitis (e.g., hydralazine, propylthiouracil), inflammatory bowel disease, primary sclerosing cholangitis, autoimmune hepatitis, and some infections. Testing supports but is not fully specific and requires clinical correlation.

Normal ANCA results vary by test and laboratory. By indirect immunofluorescence, ANCA is usually reported as negative at titers below 1:20 (or 1:10 in some labs). For antigen‑specific assays, anti‑PR3 and anti‑MPO are typically considered negative below the assay cutoff (commonly <20 U/mL; some assays use <5–10 U/mL). Always interpret with lab reference ranges and clinical context.

Cytoplasmic antineutrophil antibodies (c-ANCA, typically PR3-ANCA) are classically associated with granulomatosis with polyangiitis (GPA). Perinuclear ANCA (p-ANCA, often MPO-ANCA) link to microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis (Churg–Strauss), and renal-limited vasculitis. ANCA patterns can also appear in inflammatory bowel disease, primary sclerosing cholangitis, some drug-induced or infectious conditions, and occasionally other autoimmune disorders.

Yes. ANCA are autoantibodies that target neutrophil proteins (mainly PR3 and MPO) and are strongly associated with ANCA-associated vasculitis—small-vessel autoimmune diseases such as granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic granulomatosis. ANCAs help with diagnosis and monitoring, are implicated in disease mechanisms, and can occasionally appear in infections, drug reactions, or other autoimmune conditions.

Yes. ANCA-associated vasculitis commonly involves small kidney blood vessels, causing inflammation of the glomeruli (pauci-immune rapidly progressive glomerulonephritis). It can cause blood or protein in urine, reduced filtration, rising creatinine and may lead to acute or chronic kidney failure if untreated. Prompt diagnosis and immunosuppressive treatment are important to limit kidney damage and preserve function.