Nephropathy associated with vasculitis

Vasculitis is characterised by inflammation of vessels. We categorize vasculitides based on whether they primarily affect large, medium, or small vessels. Large vessel vasculitis can contribute to renovascular hypertension, and medium vessel vasculitis can predispose to renal infarction and haemorrhage. However, the most important vasculitides in nephrology are the small vessel vasculitides, which affect the glomeruli and arterioles.

Etiology

• Small vessel vasculitis
  • ANCA-associated vasculitis
    • Microscopic polyangiitis (MPA)
    • Granulomatosis with polyangiitis (GPA)
    • Eosinophilic granulomatosis with polyangiitis (EGPA)
  • Immunocomplexes in the vessel wall
    • Cryoglobulinaemic vasculitis
    • IgA vasculitis (Henoch-Schönlein purpura)
    • Anti-GBM disease/Goodpasture syndrome
    • SLE vasculitis
• Medium vessel vasculitis
• Large vessel vasculitis

Of these, the ANCA-associated vasculitides are the most important.

Clinical features

Vasculitides which have renal involvement also have systemic involvement, and as such they also cause extrarenal symptoms. They usually have non-specific symptoms like fever, weight loss, malaise, and joint pain. Other extrarenal symptoms include haemoptysis, purpuras, and involvement of the eyes and CNS.

GPA is especially associated with diseases of the upper respiratory tract, like sinusitis, otitis, and perforation of the nasal septum.

EGPA is especially associated with bronchial asthma.

The renal symptoms of small vessel vasculitides include decreased kidney function, proteinuria, and haematuria. They may manifest as glomerulonephritis, often as rapidly progressing glomerulonephritis.

Diagnosis and evaluation

Screening for p-ANCA and c-ANCA is essential. GPA is associated with c-ANCA, while EGPA and MPA are associated with p-ANCA, although this is completely specific or sensitive.

Renal biopsy is performed if ANCA-vasculitis is suspected. The findings (same as in RPGN) include crescents in the glomeruli and pauci-immunity on immunofluorescence.

Treatment

ANCA-vasculitides have very poor prognosis if untreated, so immunosuppressive treatment is important. The treatment is described in the RPGN topic.