Anti-Neutrophil Cytoplasmic Antibody (ANCA)
The anti-neutrophil cytoplasmic antibody (ANCA) test detects antibodies that target proteins inside your white blood cells. It is used mainly to evaluate certain types of blood-vessel inflammation.
Because ANCA is associated with a group of autoimmune conditions called ANCA-associated vasculitis, which can affect the lungs, kidneys, and other organs. The test helps a clinician assess unexplained inflammation and organ involvement. Results are often reported as patterns (such as c-ANCA or p-ANCA) that guide further testing.
A positive ANCA can be associated with forms of vasculitis such as granulomatosis with polyangiitis or microscopic polyangiitis, and the specific pattern helps narrow the possibilities. Because ANCA can occasionally appear in other conditions, a positive result is interpreted by your clinician alongside symptoms, organ findings, and sometimes a biopsy rather than on its own.
A negative ANCA makes ANCA-associated vasculitis less likely but does not completely exclude it, especially early or in limited forms. Your clinician weighs it against your symptoms and other testing.
A negative result is typical. Any positive result should be interpreted by your clinician in the context of your symptoms, organ involvement, and confirmatory testing.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.