Pulmonary renal syndromes: A pulmonologist's view

BackgroundPulmonary Renal Syndromes are heterogeneous group of disorders characterized by co-occurrence of rapidly progressive glomerulonephritis (RPGN) and alveolar hemorrhage due to an autoimmune etiology. This condition many a times presents as an emergency and can be rapidly fatal. A high index of suspicion is required to identify PRS early because appropriate diagnosis and timely institution of treatment is necessary for favorable results. The most common causes of PRS include anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV), anti-glomerular basement membrane (Anti-GBM) disease and systemic lupus erythematosus (SLE) which are responsible for almost 80% of the cases. All these condition share similar clinical presentation however there are some salient features which differentiate them in terms of prognosis and management.MethodsThis is a narrative review using the search terms; “pulmonary renal syndrome, granulomatosis with polyangiitis; eosinophilic granulomatosis with polyangiitis; microscopic polyangiitis; anti-GBM disease and systemic lupus erythematosus.ResultsThe most common causes of PRS include anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV), anti-glomerular basement membrane (Anti-GBM) disease and systemic lupus erythematosus (SLE) which are responsible for almost 80% of the cases. All these condition share similar clinical presentation however there are some salient features which differentiate them in terms of prognosis and management. The response to immunosuppressive therapy and long term prognosis also differs because of distinguishing features in pathogenesis of these disorders. There is no consensus about the management protocols of pulmonary renal syndromes however, various immunological societies have laid down treatment protocols with variable success rates.ConclusionThe syndrome of PRS has a high short-term mortality (20–40%). The rates of remission are >90% with current protocols and effective second line therapies exist for those who don't attain remission. Relapse rates are about 15% at 18 months and are higher with patients having PR3-ANCA and a diagnosis of GPA. A high index of suspicion is required to identify PRS early because treatment delays may be rapidly fatal.