Synopsis
Detect pauci-immune crescentic glomerulonephritis within multisystem ANCA-associated vasculitis, assess organ threat promptly, and support biopsy-led induction, prophylaxis and relapse-prevention care.
- Granulomatosis with polyangiitis and microscopic polyangiitis commonly cause necrotising pauci-immune crescentic GN; eosinophilic granulomatosis with polyangiitis affects kidneys less often but remains in the differential.
- PR3-ANCA is associated more often with GPA and relapse, while MPO-ANCA is associated more often with MPA and renal-limited disease; neither antibody defines phenotype perfectly.
- Haematuria, red-cell casts, proteinuria and a creatinine rise can be clinically silent, so urinalysis and serial renal function belong in every suspected systemic-vasculitis assessment.
Key red flags
Dyspnoea, hypoxia, diffuse opacities and falling haemoglobin may represent alveolar bleeding even without haemoptysis and demand critical pulmonary–renal assessment.
Investigation priorities
Identify glomerular blood, casts and protein and establish a baseline for renal response.
Management branches
AKI or falling eGFR accompanies active glomerular urine findings with or without systemic vasculitic features.
- Admit according to organ threat, assess lungs, nerves, eyes, ENT, skin and cardiovascular state, and treat hyperkalaemia, acidosis, sepsis or respiratory failure immediately.
- Send PR3, MPO, anti-GBM, complement, ANA, cultures and focused infection tests, obtain chest imaging and review medicines and cocaine exposure.
Key medicines
RituximabInduction and maintenance use a specialist intravenous protocol with premedication, screening and scheduled re-dosing.
Intravenous cyclophosphamidePulse dose and interval follow the vasculitis protocol with reductions for age, eGFR, cytopenia and cumulative exposure.