Rapidly progressive glomerulonephritis (RPGN) is a syndrome of the kidney that is characterized by a rapid loss of kidney function, (usually a 50% decline in the glomerular filtration rate (GFR) within 3 months) with glomerular crescent formation seen in at least 50% or 75% of glomeruli seen on kidney biopsies. If left untreated, it rapidly progresses into acute kidney failure and death within months. In 50% of cases, RPGN is associated with an underlying disease such as Goodpasture syndrome, systemic lupus erythematosus or granulomatosis with polyangiitis; the remaining cases are idiopathic. Regardless of the underlying cause, RPGN involves severe injury to the kidneys glomeruli, with many of the glomeruli containing characteristic glomerular crescents (crescent-shaped scars). Signs and symptoms
Most types of RPGN are characterized by severe and rapid loss of kidney function with marked hematuria; red blood cell casts in the urine; and proteinuria sometimes exceeding three grams in twenty-four hours, a range associated with nephrotic syndrome. Some patients also experience hypertension and edema. Severe disease is characterized by pronounced oliguria or anuria, which portends a poor prognosis. Pathophysiology
It is thought that antineutrophil cytoplasmic antibodies (ANCA) interact with antigens in the cytoplasm of neutrophils to cause an early degranulation, triggering the release of lytic enzymes at the site of injury and leading to the formation of glomerular crescents that consist primarily of parietal epithelial cells from Bowmans capsule and in some cases podocytes. Diagnosis
Serum analysis often aids in the diagnosis of a specific underlying disease.
Other diagnostic tests are useful in excluding other similar conditions, but history, X-ray, and biopsy are essential. These other tests may include basic blood work, blood cultures, and bronchoalveolar lavage. The clinical picture is similar to ARDS, but AIP differs from ARDS in that the cause for AIP is not known. Treatment
Treatment is primarily supportive. Management in an intensive care unit is required and the need for mechanical ventilation is common. Therapy with corticosteroids is generally attempted, though their usefulness has not been established. The only treatment that has met with success to date is a lung transplant. Prognosis
Sixty percent of people with acute interstitial pneumonitis will die in the first six months of illness. The median survival is 1+1⁄2 months. However, most people who have one episode do not have a second. People who survive often recover lung function completely. Epidemiology
Acute interstitial pneumonitis occurs most frequently among people older than forty years old. It affects men and women equally. There are no known risk factors; in particular, smoking is not associated with increased risk. History
Acute interstitial pneumonitis was first described in 1935 by Louis Hamman and Arnold Rich, and given the name Hamman–Rich syndrome. References
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synd/3010 at Who Named It? 00181 at CHORUS