Urinary erythrocyte morphology as a diagnostic aid in haematuria

The value of urinary erythrocyte morphology in diagnosing glomerular and nonglomerular haematuria was studied using phase contrast microscopy in 105 patients with significant haematuria. Fifty-eight (93.6%) out of 62 patients with glomerulonephritis had dysmorphic erythrocytes and 40 (93.1%) out of the 43 patients with nonglomerular disease had isomorphic erythrocytes in the urine. A mixed picture of glomerular and nonglomerular haematuria was seen in 5 patients. The sensitivity was 93.6%, the specificity was 97.7% and the positive predictive value was 98.3% for glomerulonephritis in patients with dysmorphic haematuria. The positive predictive value for a nonglomerular source of bleeding was 96.7% with isomorphic haematuria. It is concluded that phase contrast microscopic examination of erythrocytes in urine is a simple, inexpensive and noninvasive technique that reliably distinguishes between glomerular and nonglomerular bleeding in patients.