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Pulmonary-Renal Syndrome


Joyce Lee

, MD, MAS, University of Colorado School of Medicine

Last full review/revision Sep 2021| Content last modified Sep 2021
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Pulmonary-renal syndrome is not a specific entity but is a syndrome that has a specific differential diagnosis and a specific sequence of testing.

Pulmonary pathology is small-vessel vasculitis involving arterioles, venules, and, frequently, alveolar capillaries.

Renal pathology is small-vessel vasculitis resulting in a form of focal segmental proliferative glomerulonephritis.

Etiology of Pulmonary-Renal Syndrome

Pulmonary-renal syndrome is almost always a manifestation of an underlying autoimmune disorder. Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, a subtype of pulmonary-renal syndrome, is an autoimmune syndrome consisting of alveolar hemorrhage and glomerulonephritis caused by circulating anti-glomerular basement... read more Goodpasture Syndrome is the prototype cause, but pulmonary-renal syndrome can also be caused by systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more Systemic Lupus Erythematosus (SLE) , granulomatosis with polyangiitis Granulomatosis with Polyangiitis (GPA) Granulomatosis with polyangiitis is characterized by necrotizing granulomatous inflammation, small- and medium-sized vessel vasculitis, and focal necrotizing glomerulonephritis, often with crescent... read more Granulomatosis with Polyangiitis (GPA) , microscopic polyangiitis Microscopic Polyangiitis (MPA) Microscopic polyangiitis is a systemic necrotizing vasculitis without immune globulin deposition (pauci-immune) that affects mainly small vessels. It may begin as a pulmonary-renal syndrome... read more Microscopic Polyangiitis (MPA) , and, less commonly, by other vasculitides, connective tissue disorders, and drug-induced vasculitides (eg, propylthiouracil—see table Causes of Pulmonary-Renal Syndrome Causes of Pulmonary-Renal Syndrome Pulmonary-renal syndrome is diffuse alveolar hemorrhage plus glomerulonephritis, often occurring simultaneously. Cause is almost always an autoimmune disorder. Diagnosis is by serologic tests... read more ).


Symptoms and Signs of Pulmonary-Renal Syndrome

Symptoms and signs typically include

  • Cough

  • Dyspnea

  • Fever

  • Hematuria

  • Hemoptysis

  • Peripheral edema

Pearls & Pitfalls

  • Consider pulmonary-renal syndrome in patients with findings compatible with alveolar hemorrhage and glomerulonephritis even when pulmonary and renal findings occur at different times.

Diagnosis of Pulmonary-Renal Syndrome

  • Serologic testing

  • Sometimes lung and kidney biopsies

Initial testing includes urinalysis for evidence of hematuria and red cell casts (suggesting glomerulonephritis), serum creatinine for renal function assessment, and CBC for evidence of anemia. Chest x-ray is done if not yet obtained.

Serum antibody testing may help distinguish some causes, as in the following:

Definitive diagnosis requires lung biopsy with findings of small-vessel vasculitis or renal biopsy with findings of glomerulonephritis with or without antibody deposition.

Pulmonary function tests Overview of Tests of Pulmonary Function Pulmonary function tests provide measures of airflow, lung volumes, gas exchange, response to bronchodilators, and respiratory muscle function. Basic pulmonary function tests available in the... read more and bronchoalveolar lavage are not diagnostic but can be used to help confirm diffuse alveolar hemorrhage in patients with glomerulonephritis and pulmonary infiltrates but without hemoptysis. Lavage fluid that remains hemorrhagic after sequential sampling establishes diffuse alveolar hemorrhage, especially when hematocrit is falling.

Treatment of Pulmonary-Renal Syndrome

  • Corticosteroids

  • Sometimes cyclophosphamide

  • Plasma exchange

Immunosuppression is the cornerstone of treatment of pulmonary-renal syndrome. Standard induction-remission regimens include pulse IV methylprednisolone (500 to 1000 mg IV once a day for 3 to 5 days). As life-threatening features subside, the corticosteroid dose can be reduced; 1 mg/kg prednisone (or equivalent) orally once a day is given for the first month, then tapered over the next 3 to 4 months.

Cyclophosphamide should be added to corticosteroid therapy in critically ill patients with generalized disease, at a dose of 0.5 to 1 g/m2 IV given as a pulse once a month or orally (1 to 2 mg/kg once a day). Rituximab may be used instead of cyclophosphamide; it is non-inferior and causes fewer adverse effects.

Transition to maintenance therapy may occur 6 to 12 months after the initiation of induction therapy or after clinical remission. Maintenance therapy includes low-dose corticosteroids coupled with cytotoxic agents. However, relapse may occur despite ongoing therapy.

Key Points

  • The most suggestive clue to pulmonary-renal syndrome is often that patients have both unexplained pulmonary and renal symptoms, even when such symptoms occur at different times.

  • Do routine laboratory tests (including urinalysis and chest x-ray) as well as autoantibody testing.

  • Confirm the diagnosis when necessary with lung or kidney biopsy.

  • Treat underlying autoimmune disorders.

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