Investigations for granulomatosis with polyangiitis

Investigations commonly performed for most systemic vasculitides (including granulomatosis with polyangiitis) are outlined in Investigations for systemic vasculitides. Investigations that may support a specific diagnosis of granulomatosis with polyangiitis include:

• positive antineutrophil cytoplasmic antibody (ANCA) with the cytoplasmic (cANCA) staining pattern and anti-proteinase-3 (PR-3) specificity in most patients
• characteristic changes on biopsy of affected tissue (eg paranasal sinus, laryngeal, periorbital, oral, external ear, middle ear, mastoid, salivary gland, kidney)Yates, 2016
• elevated serum creatinine concentration—kidney involvement usually signals a poor prognosis.