Investigations for eosinophilic granulomatosis with polyangiitis

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

• blood eosinophilia of greater than 1×10⁹/L (normal range less than 0.6×10⁹/L)
• positive antineutrophil cytoplasmic antibody (ANCA) with a perinuclear (pANCA) staining pattern—seen in approximately one-third of patients
• characteristic changes may be seen on biopsy of affected tissue (eg lung)—small necrotising granulomas or necrotising vasculitis with frequent eosinophils
• elevated serum creatinine concentration—kidney involvement usually signals a poor prognosis.