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For further information, see CMDT Part 22-15: Nephritic Spectrum Glomerular Diseases

Key Features

  • ANCA-associated vasculitides that cause pauci-immune necrotizing glomerulonephritis

    • Granulomatosis with polyangiitis

    • Microscopic polyangiitis

    • Eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome)

  • Antineutrophil cytoplasmic antibody (ANCA)–associated glomerulonephritis can also present as a kidney-limited disease without systemic vasculitis

  • Circulating ANCAs bind to antigens and activate a neutrophil respiratory burst with consequent vascular damage; primed neutrophils also appear to activate the alternative complement pathway

  • Renal involvement classically presents as a rapid progressive glomerulonephritis, but more indolent presentations can be seen as well

  • Putative environmental exposures that may incite the initial response include Staphylococcus aureus and silica

  • Immunofluorescence of kidney biopsy specimens do not reveal any evidence of immunoglobulin or complement deposition, hence the term "pauci-immune"

  • Most cases are idiopathic, but others may be linked

    • To an infection (including COVID-19)

    • Environmental exposure (silica)

    • To a drug (hydralazine or levamisole)

Clinical Findings

  • Fever, malaise, and weight loss, may be present, sometimes for months

  • Hematuria and proteinuria

  • Purpura and mononeuritis multiplex

  • Sinus or lower respiratory tract symptoms present in 90% of patients with granulomatosis with polyangiitis

  • Hemoptysis may be a sign of alveolar hemorrhage


  • ANCA subtype analysis is done to determine whether antiproteinase-3 antibodies (PR3-ANCA) or antimyeloperoxidase antibodies (MPO-ANCA) are present

  • Most patients with granulomatosis with polyangiitis are PR3 positive; the remainder are MPO positive or, rarely, do not demonstrate circulating ANCA

  • Microscopic angiitis is generally associated with MPO ANCA

  • Kidney biopsy demonstrates necrotizing lesions and crescents on light microscopy

  • Immunofluorescence is negative for immune complex deposition ("pauci-immune")


  • Institute treatment early if aggressive disease is present; prognosis depends mainly on extent of renal involvement before treatment is started

  • Hemoptysis usually warrants hospitalization and aggressive immunosuppression

  • Induction therapy

    • High-dose corticosteroids (methylprednisolone, 1–2 g/day intravenously for 3 days, followed by prednisone, 1 mg/kg orally for 1 mo, with a slow taper over the next 6 mo) and cytotoxic agents (cyclophosphamide, 0.5–1.0 g/m2 intravenously per month or 1.5–2 mg/kg orally for 3–6 months)

  • Maintenance of remission: Long-term azathioprine or mycophenolate mofetil

  • Rituximab

    • Shown to be noninferior to cyclophosphamide for induction

    • Also used in refractory or relapsing cases and as an alternative to azathioprine for maintenance of remission

  • Avacopan

    • Oral complement inhibitor

    • Shown to be noninferior to oral glucocorticoids for induction in patients treated with either cyclophosphamide or rituximab

  • Plasma exchange is likely helpful in conjunction with induction therapy for cases complicated by pulmonary hemorrhage

  • Monitor ANCA levels to help determine efficacy of treatment

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