INFLUENCE OF URINARY CALCIUM-CONCENTRATION ON ERYTHROCYTE MORPHOLOGY

The effect of the urinary calcium concentration (CaU) on erythrocyte m orphology was studied by incubating erythrocytes in urine with prefixe d CaUs of 5, 10, 20 and 40 mmol/l by addition of CaCl2. The same exper iment was carried out on erythrocytes preincubated with levo-verapamil (I-V) at 10, 100 and 200 mu mol/l. Phase contrast microscopy observat ions were performed at 0, 30, 60, 120, and 240 min by 2 experienced in vestigators. At 0 min the erythrocytes showed a clear extraglomerular pattern. At 60 min marked morphological and volumetric alterations wer e evident when the CaU was greater than or equal to 10 mmol/l. On the contrary, no change was found when red cells were treated with greater than or equal to 100 mu mol/l l-V, independent of the CaU. Dysmorphic erythrocyturia has been related to transglomerular passage even if it was sporadically observed in hypercalciuric or lithiasic patients. Th is work suggests a role for a high CaU in causing the formation of mic rocytic and warped erythrocytes. In our opinion, in hypercalciuric uri ne the appearance of dysmorphic or mixed hematuria does not necessaril y indicate transglomerular passage.