Beta-estradiol and ethinylestradiol enhance RBC deformability dependent on their blood concentration

BACKGROUND: Natural and synthetic estrogens seems to have opposite effects on thrombosis and female cardiovascular system, since natural estrogen was supposed to be protective against cardiovascular diseases and synthetic estrogen has been related to thrombosis and cardiovascular diseases. In this work we have investigated if these differences could be related with the effects on those hormones on some hemorheological parameters. OBJECTIVE: The objective of this work was to investigate the hemorheological changes of different concentrations of beta-estradiol and ethinylestradiol, on RBC aggregation and RBC deformability. METHODS: Samples of blood of healthy donors were added with different concentrations of natural beta-estradiol or synthetic ethinylestradiol and were analyzed for red blood cell (RBC) aggregation and RBC deformability. RESULTS: There were no significant changes in RBC aggregation. Both beta-estradiol and ethinylestradiol increase the RBC deformability in shear stresses above 3.0 Pa accordingly with the hormone's concentration. CONCLUSIONS: Beta-estradiol and ethinylestradiol enhance RBC deformability dependent of their concentration. These findings may explain the different patterns of thrombotic and cardiovascular effects in different phases of the menstrual cycle or different dosages of oral contraceptive or hormonal replacement therapy.