The Journal of laboratory and clinical medicine
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Low cell calcium level is essential for preservation of red blood cell (RBC) membrane deformability and survival. RBCs from patients with end-stage renal disease (ESRD) demonstrate reduction in membrane deformability, possibly as a result of increased RBC cellular calcium level. To evaluate calcium homeostasis in RBCs from patients with ESRD, we measured cell calcium level, basal and "calmodulin"-stimulated calcium-stimulated Mg-dependent ATPase (CaATPase) activity, and calcium 45 efflux were measured before and after hemodialysis. ⋯ These results indicate that RBC calcium level is elevated in patients with ESRD and suggest that a dialyzable uremic factor inhibits RBC CaATPase activity and thereby calcium efflux, which may account for the elevated cell calcium level. The increased calcium influx further increases cellular calcium level. These abnormalities are associated with spherocytosis and echynocytosis and may contribute to the shortened survival of RBCs in uremia.