Relation between echinocytosis and erythrocyte calcium content in hemodialyzed uremic patients.

A rise in intracellular calcium concentration in erythrocytes has multiple effects on these cells. The purpose of this study was to determine the changes of calcium content in red blood cells (RBCs) and of echinocyte percentages in uremic patients during hemodialysis sessions. In 30 uremic patients under hemodialysis, the calcium content of RBCs and echinocyte percentages were determined in 3 blood samples collected at 0 min hemodialysis (prehemodialysis), 45 min hemodialysis, and 240 min hemodialysis (end hemodialysis) for a 4 h hemodialysis session. Calcium content of RBCs and echinocytes were also determined in 22 normal subjects (controls). The findings of the present study were that the mean values (+/-SD) of calcium content of RBCs in patients at 0 min hemodialysis, 45 min hemodialysis, and 240 min hemodialysis were 2.00 +/- 1.0, 2.66 +/- 0.87, and 1.62 +/- 0.66 microg/ml respectively and 0.65 +/- 0.07 microg/ml in controls. These values show that the calcium content of RBCs in uremic patients at 0 min hemodialysis, 45 min hemodialysis, and 240 hemodialysis was significantly higher than in controls (p < 0.0001), and that RBC calcium content at 45 min hemodialysis was significantly higher in comparison to that at 0 min hemodialysis (p < 0.001) and to that at 240 min hemodialysis (p < 0.0001), while that at 240 min hemodialysis was significantly lower than at 0 min hemodialysis (p < 0.05). The mean values (+/-SD) of echinocyte percentages in patients at 0 min hemodialysis, 45 min hemodialysis, and 240 hemodialysis were 11.93 +/- 6.18, 17.23 +/- 4.1, and 7.96 +/- 5.67% respectively, and in controls ranged from 0 to 1%. The values in uremic patients show a transient increase of echinocyte percentages at 45 min hemodialysis, which is significant in comparison to that at 0 min hemodialysis (p < 0.001) and to that at 240 min hemodialysis (p < 0.0001). Echinocyte percentages at 240 min hemodialysis were significantly lower to those at 0 min hemodialysis (p < 0.001). Correlation between calcium content of erythrocytes and echinocyte percentages shows a significantly positive relationship at 45 min hemodialysis (r = 0.368, p < 0.05) but no significant relationship at 0 min hemodialysis and 240 min hemodialysis. In conclusion, uremic patients under hemodialysis present with high calcium content in erythrocytes and abnormal erythrocytes like echinocytes. A rapid and transient increase of erythrocyte calcium is also accompanied by transient elevation of echinocytes in the first hour of hemodialysis (45 min hemodialysis), which returns after hemodialysis to lower than prehemodialysis levels.