26th June 2023

Pulmonary-renal syndrome

Pulmonary-renal syndrome (PRS) is a dramatic presentation with renal and respiratory failure and has a high mortality rate. It occurs as a consequence of ANCA-positive vasculitis or of Goodpasture syndrome (also known as anti-glomerular basement membrane (anti-GBM) disease). PRS should be considered in anyone presenting with symptoms consistent with pulmonary haemorrhage and small vessel vasculitis. The way to differentiate GPA (granulomatosis with polyangiitis) from anti-GBM disease is the involvement of the upper respiratory tract, which will occur in GPA but never in anti-GBM disease.

The exact cause of anti-GBM disease is unknown but there is a predisposition in those individuals who exhibit HLA-DR15. Anti-GBM antibodies target a domain of the alpha-3 chain of type 4 collagen, which is predominantly found in the basement membranes of glomerular and alveolar capillaries, explaining the pulmonary and renal involvement of this disease. The most accurate way of achieving a diagnosis is with a renal biopsy.

PRS can also occur in pesticide poisoning with compounds such as paraquat or infection with legionella and leptospirosis. Cardiogenic shock can mimic a pulmonary renal syndrome and lead to haemoptysis due to pulmonary oedema and renal failure secondary to inadequate kidney blood flow. Treatment of PRS is predominantly with immunosuppressive medications such as steroids, cyclophosphamide, and rituximab to prevent the formation of new antibodies. In severe cases, plasmapheresis may be required to filter out the antibodies in the plasma.