ANCA Testing Demystified: When to Order, How to Interpret, and When to Leave It Alone
ANCA Testing Demystified: When to Order, How to Interpret, and When to Leave It Alone Vasculitis serologies are powerful—but ordering them for the wrong reasons creates more problems than it solves. ANCA testing is one of the most misused lab panels in primary care. It gets ordered for vague joint pain, nonspecific rashes, or an elevated ESR—and then a low-positive p-ANCA comes back, everyone panics, and the patient gets a workup they never needed. Meanwhile, the patient with bloody nasal crusting and rising creatinine who actually has vasculitis sometimes gets missed because nobody thought to test. Let's fix that. What Is ANCA, and What Are We Actually Testing? ANCA stands for Anti-Neutrophil Cytoplasmic Antibodies . These are autoantibodies directed against proteins inside neutrophils, and they're the serologic hallmark of a group of rare, serious, small-vessel vasculitides collectively called ANCA-associated vasculitis (AAV) . AAV includes three disease...