🫁🫘 Pulmonary-renal syndrome is a medical emergency caused by simultaneous diffuse alveolar haemorrhage and rapidly progressive glomerulonephritis. Suspect it in a patient with haemoptysis, breathlessness or new pulmonary infiltrates plus AKI, haematuria or proteinuria. The major causes are ANCA-associated vasculitis and anti-GBM disease, and early renal/respiratory/rheumatology involvement is essential.

🧬 Main Causes

Cause	Clues	Key tests
ANCA-associated vasculitis GPA / MPA / EGPA	Systemic illness, sinus/ENT disease, cough, haemoptysis, purpura, neuropathy, renal impairment.	ANCA, PR3/MPO antibodies, urinalysis, renal function, renal biopsy.
Anti-GBM disease Goodpasture disease	Haemoptysis + rapidly progressive renal failure; may follow smoking, infection or hydrocarbon exposure.	Anti-GBM antibodies, renal biopsy with linear IgG staining.
SLE / immune-complex disease	Young patient, rash, arthritis, serositis, cytopenias, nephritis.	ANA, dsDNA, ENA, complement C3/C4, urine protein:creatinine ratio.
Other vasculitis / systemic disease	Sepsis, cryoglobulinaemia, IgA vasculitis, antiphospholipid syndrome, drug-induced vasculitis.	Clinical context, cultures, complement, viral serology, immunology screen.

⚠️ Clinical Features

Pulmonary: haemoptysis, dyspnoea, cough, hypoxia, diffuse infiltrates; haemoptysis may be absent.
Renal: AKI, haematuria, proteinuria, red cell casts, hypertension, oedema.
Systemic: fever, weight loss, arthralgia, rash, neuropathy, sinus disease or constitutional symptoms.

🔍 Initial Assessment

Assess ABC, oxygen requirement, haemodynamic status and need for HDU/ICU.
Urine dip: blood and protein are key bedside clues.
Bloods: FBC, U&E/eGFR, CRP/ESR, LFT, clotting, group and save, ABG/VBG if hypoxic.
Immunology: ANCA, PR3/MPO, anti-GBM, ANA, dsDNA, complement C3/C4.
Exclude mimics: infection, pulmonary oedema, anticoagulant-related bleeding, malignancy and pulmonary embolism.

🖼️ Imaging / Procedures

CXR/CT chest: bilateral alveolar infiltrates or ground-glass change may suggest alveolar haemorrhage.
Bronchoscopy/BAL: may confirm diffuse alveolar haemorrhage and exclude infection, especially before heavy immunosuppression.
Renal biopsy: often confirms diagnosis and guides prognosis, but treatment may need to start before biopsy if life-threatening disease.

🛠️ Initial Management

Escalate early: renal, respiratory, rheumatology and ICU input if hypoxic or unstable.
Supportive: oxygen, transfusion if needed, stop anticoagulants/antiplatelets if safe, treat hyperkalaemia/acidosis/fluid overload.
Immunosuppression: high-dose corticosteroids plus rituximab or cyclophosphamide depending on cause, severity and specialist advice.
Plasma exchange: important in anti-GBM disease; may be considered in ANCA vasculitis with severe renal disease or hypoxic diffuse alveolar haemorrhage.
Renal replacement therapy: if severe AKI with refractory hyperkalaemia, acidosis, pulmonary oedema or uraemic complications.

🧠 Teaching Point

Do not wait for haemoptysis: diffuse alveolar haemorrhage can present with breathlessness, falling Hb and bilateral infiltrates. The renal clue is usually an “active urinary sediment” — blood, protein and red cell casts — suggesting glomerulonephritis rather than simple pre-renal AKI.

📚 References

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Pulmonary-renal syndromes ✅