Nephritic syndrome is defined by hematuria, variable degrees of proteinuria, usually dysmorphic red blood cells (RBCs), and often RBC casts on microscopic examination of urinary sediment. Often 1 of the following elements are present: edema, hypertension, elevated serum creatinine, and oliguria. Nephritic syndrome has both primary and secondary causes. Diagnosis is based on history, physical examination, and sometimes renal biopsy. Treatment and prognosis vary by cause.
(See also Overview of Glomerular Disorders.)
Nephritic syndrome is a manifestation of glomerular inflammation (glomerulonephritis) and occurs at any age. Causes differ by age (see table Glomerular Disorders by Age and Presentation), and mechanisms differ by cause. The syndrome can be
Acute (serum creatinine rises over many weeks or less)
Chronic (renal insufficiency may progress over years)
Nephritic syndrome can also be
Primary (idiopathic)
Secondary
Acute glomerulonephritis
Postinfectious glomerulonephritis is the prototype of acute glomerulonephritis, but the condition may be caused by other glomerulopathies and by systemic disorders such as systemic rheumatic diseases and hematologic dyscrasias (see table Causes of Glomerulonephritis).
Rapidly progressive glomerulonephritis (RPGN) is an acute glomerulonephritis resulting from the secondary sequelae of inflammatory (crescenteric) glomerulonephritis, of which there are many causes. RPGN is a pathologic diagnosis.
Chronic glomerulonephritis
Chronic glomerulonephritis has features similar to those of acute glomerulonephritis but develops slowly and may cause mild to moderate proteinuria. Examples include
