Idiopathic Focal Proliferative Nephritis Associated with Persistent Hematuria and Normal Renal Function

Abstract

Thirty-three patients with "active" urinary sediments (containing red cells and red cell or heme granular casts) that have persisted up to 10 years without significant deterioration in renal function are described. Fourteen patients presented with sore throat or gross hematuria, or both, and the other 19 were discovered through abnormal routine urinalyses. Since no difference was observed in most of their clinical, renal functional, or histological features, both groups are considered to represent the same disease process. No patient had edema, renal hypertension, or evidence of a systemic disease. In all cases most glomeruli seen in renal biopsies were normal. When lesions were observed, a focal, usually segmental, proliferative glomerulonephritis predominated. These cases probably represent a form of focal, proliferative nephritis of presently unknown cause. The differential diagnosis between this condition, acute poststreptococcal nephritis, and "latent chronic" glomerulonephritis is discussed. The distinction is important because idiopathic focal proliferative nephritis may have not only a different cause but also a more benign prognosis.