EVALUATION OF ASYMPTOMATIC MICROSCOPIC HEMATURIA - INFLUENCE AND CLINICAL RELEVANCE OF OSMOLALITY AND PH ON URINARY ERYTHROCYTE MORPHOLOGY

Objective To determine whether the morphological distinction between ' dysmorphic' and 'eumorphic' erythrocytes in urinary sediment different iates microscopic haematuria (MH) from reno-parenchymal and post-renal bleeding. Materials and methods The erythrocyte morphology of 2145 ur inary sediments from 1391 patients with MH was evaluated by interferen ce-contrast microscopy and compared with the osmolality, pH and specif ic gravity of the urine samples, Results Compared with more concentrat ed urine specimens, samples of <700 mOsmol/kg showed significantly low er percentages of dysmorphic erythrocytes; there was a similar reducti on in this percentage at a pH greater than or equal to 7. In addition, erythrocytes lysed in diluted or alkaline urine and therefore, under these conditions, no diagnosis could be made. Conclusion The assessmen t of erythrocytes in urinary sediment should be performed only under ' standard conditions', i.e. in concentrated and acidic urine, greater t han or equal to 700 mOsmol/kg and a pH<7, The presence of greater than or equal to 90% dysmorphic erythrocytes in patients with asymptomatic MH, the absence of proteinuria, a normal blood pressure and normal ra diological examination indicates 'reno-parenchymal MH', requiring a lo ng-term follow-up with a routine evaluation twice a year, but no immed iate treatment in most cases. In contrast, the presence of greater tha n or equal to 90% eumorphic erythrocytes or even 'mixed' results (10-9 0% eumorphic erythrocytes) indicates 'post-renal MH', requiring a comp lete urological evaluation.