[How do I treat ANCA vasculitis with renal involvement].

ANCA-associated vasculitis, such as granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA), are rare systemic diseases causing necrotizing inflammation of small blood vessels. Renal involvement is common, leading to acute kidney injury with hematuria and proteinuria. Diagnosis is based on serological tests (PR3-ANCA, MPO-ANCA) and renal histology via biopsy, which helps assess the extent of lesions. Scores and classifications have been validated to predict the progression toward end-stage renal disease. Therapeutically, induction treatment (3 to 6 months) relies on corticosteroids combined with immunosuppressants such as cyclophosphamide or rituximab. Maintenance therapy (24 to 48 months) aims to prevent relapses, with rituximab proving superior to azathioprine. Avacopan, a C5a receptor inhibitor, offers a promising alternative by reducing dependence on corticosteroids in the induction phase. The KDIGO 2024 guidelines recommend early kidney biopsy and advise the use of these immunosuppressive treatments according to standardized protocols. These guidelines also integrate innovative therapeutic options like avacopan, providing new perspectives in the management of ANCA-associated vasculitis.