OBJECTIVE: To determine whether the morphological distinction between 'dysmorphic' and 'eumorphic' erythrocytes in urinary sediment differentiates microscopic haematuria (MH) from reno-parenchymal and post-renal bleeding. MATERIALS AND METHODS: The erythrocyte morphology of 2145 urinary sediments from 1391 patients with MH was evaluated by interference-contrast microscopy and compared with the osmolality, pH and specific gravity of the urine samples. RESULTS: Compared with more concentrated urine specimens, samples of < 700 mOsmol/kg showed significantly lower percentages of dysmorphic erythrocytes; there was a similar reduction in this percentage at a pH > or = 7. In addition, erythrocytes lysed in diluted or alkaline urine and therefore, under these conditions, no diagnosis could be made. CONCLUSION: The assessment of erythrocytes in urinary sediment should be performed only under 'standard conditions', i.e. in concentrated and acidic urine, > or = 700 mOsmol/kg and a pH < 7. The presence of > or = 90% dysmorphic erythrocytes in patients with asymptomatic MH, the absence of proteinuria, a normal blood pressure and normal radiological examination indicates 'reno-parenchymal MH', requiring a long-term follow-up with a routine evaluation twice a year, but no immediate treatment in most cases. In contrast, the presence of > or = 90% eumorphic erythrocytes or even 'mixed' results (10-90% eumorphic erythrocytes) indicates 'post-renal MH', requiring a complete urological evaluation.
OBJECTIVE: To determine whether the morphological distinction between 'dysmorphic' and 'eumorphic' erythrocytes in urinary sediment differentiates microscopic haematuria (MH) from reno-parenchymal and post-renal bleeding. MATERIALS AND METHODS: The erythrocyte morphology of 2145 urinary sediments from 1391 patients with MH was evaluated by interference-contrast microscopy and compared with the osmolality, pH and specific gravity of the urine samples. RESULTS: Compared with more concentrated urine specimens, samples of < 700 mOsmol/kg showed significantly lower percentages of dysmorphic erythrocytes; there was a similar reduction in this percentage at a pH > or = 7. In addition, erythrocytes lysed in diluted or alkaline urine and therefore, under these conditions, no diagnosis could be made. CONCLUSION: The assessment of erythrocytes in urinary sediment should be performed only under 'standard conditions', i.e. in concentrated and acidic urine, > or = 700 mOsmol/kg and a pH < 7. The presence of > or = 90% dysmorphic erythrocytes in patients with asymptomatic MH, the absence of proteinuria, a normal blood pressure and normal radiological examination indicates 'reno-parenchymal MH', requiring a long-term follow-up with a routine evaluation twice a year, but no immediate treatment in most cases. In contrast, the presence of > or = 90% eumorphic erythrocytes or even 'mixed' results (10-90% eumorphic erythrocytes) indicates 'post-renal MH', requiring a complete urological evaluation.