what is anca blood test?
 Tests for antineutrophil cytoplasmic antibodies (ANCA) may be used to: Help detect and diagnose certain forms of autoimmune vasculitis, including granulomatosis with polyangiitis (Wegener granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (Churg Strauss syndrome). 