Urinary erythrocyte morphology in the diagnosis of glomerular hematuria.

Urine samples from 141 consecutive patients referred for investigation of microscopic hematuria were examined by phase-contrast microscopy to determine the probable site of bleeding into the urinary tract. Dysmorphic (i.e. morphologically variable) erythrocytes, suggestive of glomerular bleeding, were present in 86 of 87 patients with significant hematuria who were later shown to have glomerulonephritis. In contrast, all of 30 patients with non-glomerular lesions had isomorphic (i.e. morphologically uniform) erythrocytes in the urine. Ten patients yielded a mixed morphologic pattern suggestive of dual pathology which was confirmed in four patients. Urine erythrocyte counts from 376 healthy individuals showed that 95% yielded less than 8,000 cells/ml and in each case erythrocytes exhibited a dysmorphic pattern suggesting that erythrocytes enter the urine of healthy subjects via the glomerulus. Electron microscopy of urinary erythrocytes from 36 patients with glomerulonephritis demonstrated the range of dysmorphic changes characteristic of glomerular bleeding, presumably resulting from environmental changes suffered by the erythrocytes within renal tubules.