Features of acute nephritis, focal necrosis with/without crecents, and rapidly progressive renal failure over weeks; treatable cause of acute renal failure

Aetiology

• ANCA positive
  • Systemic vasculitis - GPA, microscopic polyangiitis
• ANCA negative
  • Goodpasture's disease - anti-GBM
  • HSP
  • SLE

Clinical features

• Rapid deterioration in renal function over days/weeks
• Active urinary sediment (RBCs, RBC and granular casts)
• May be part of systemic disease

Investigations

• Urine: active urinary sediment (RBCs, RBC and granular casts)
• Renal biopsy: glomerular crescents

Management

• Immunosuppression
  • Steroids - IV methylprednisolone/oral prednisolone
  • Cytotoxics - cyclophosphamide/mycophenolate/azathioprine
• Plasmapharesis
• Supportive care including dialysis if needed