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Pulmonary-Renal Syndrome

By

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

Table

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.

Drugs Mentioned In This Article

Drug Name Select Trade
No US brand name
No US brand name
MEDROL
RAYOS
RITUXAN
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