Synopsis
Recognise granulomatosis with polyangiitis across ENT, lung, kidney, eye and nerve systems, confirm vasculitis with targeted serology and tissue, and deliver severity-matched induction, maintenance and infection prevention without waiting for irreversible organ loss.
- Think GPA when chronic destructive sinus or ear disease, epistaxis, nasal crust, hearing loss, pulmonary nodules or haemorrhage, glomerular urine, scleritis or mononeuritis occur together.
- Obtain FBC, CRP or ESR, creatinine, electrolytes, urinalysis, microscopy and quantitative protein immediately; a small creatinine rise can represent substantial loss from a low baseline.
- Request PR3-ANCA and MPO-ANCA by antigen-specific immunoassay, but do not diagnose from ANCA alone or exclude tissue-proven disease after a negative result.
Key red flags
Haemoptysis may be absent in diffuse alveolar haemorrhage; falling haemoglobin, hypoxia and diffuse opacities with active urine is an emergency.
Multiple nodules, cavities or diffuse opacities with falling haemoglobin and hypoxia suggest granulomatous lung disease or alveolar haemorrhage.
Investigation priorities
Detect glomerulonephritis early and quantify renal trajectory and complications.
Management branches
ENT, lung, kidney, eye or nerve findings form a credible GPA pattern.
- Assess physiology and threatened organs, obtain blood, urine, PR3 or MPO assays, cultures and CT chest or affected anatomy.
- Choose the highest-yield safe biopsy, commonly kidney with active sediment, and send necrotic respiratory tissue for microbiology.
Key medicines
RituximabLicensed adult induction uses 375 mg/m² intravenously once weekly for four doses; 1,000 mg on days 1 and 15 is a common off-label specialist alternative. Licensed maintenance begins with two 500 mg infusions two weeks apart, then 500 mg every six months for at least 24 months; after rituximab induction, wait at least 16 weeks from the final induction infusion.
Intravenous cyclophosphamideA common pulse regimen is 15 mg/kg intravenously at weeks 0, 2 and 4 and then every three weeks for three to six further pulses, reduced for age, renal function and leukopenia.