Renal disease in small-vessel vasculitis.

Glomerulonephritis (GN) is a common manifestation of the antineutrophil cytoplasmic antibody-associated systemic vasculitides (AASV), which include granulomatosis with polyangiitis and microscopic polyangiitis. The level of renal involvement at presentation is highly predictive of survival and should be assessed early so that kidney function can be preserved. AASV patients with urinary sediment but normal function have a twofold greater risk of death than those with no renal involvement. Those with impaired renal function at diagnosis have a fivefold greater risk of death. Renal vasculitis is most prevalent in older patients, who have more severe disease and poorer prognoses. Renal biopsy not only establishes diagnosis but provides information on severity of renal-function impairment and prognosis. Induction of remission with cyclophosphamide is standard treatment. For patients with crescentic, rapidly progressive GN, adjunctive plasma exchange can promote renal recovery. Renal failure occurs in one-fourth of AASV patients after 3 to 4 years; 60% of patients receiving dialysis for acute GN can recover independent renal function. Renal transplant patients with vasculitis fare as well as renal transplant patients without vasculitis. Lastly, renal vasculitis is an independent risk factor for cardiovascular events.