Effect of hormone replacement therapy upon haemorheological variables.

It is already admitted that hormone replacement therapy (HRT) decreases the risk of developing cardiovascular disease, although its mechanism is not clear yet. In the present work, the effect of the HRT upon cellular and plasmatic haemorheological factors determining blood flow properties: blood viscosity, plasma viscosity, plasma fibrinogen, rigidity erythrocyte index and erythrocyte aggregation rate was studied. Menopausal women were followed through a whole year of HTR. Results demonstrate that after six months of treatment there is a diminution in relative blood viscosity and erythrocyte rigidity, with constant values along the second semester. Erythrocyte aggregation, plasmatic and blood viscosity diminution observed during the treatment can be explained by the simultaneous plasma fibrinogen decrease. Modified cellular and plasmatic rheology could produce beneficial effects on blood flow, particularly in microcirculation, presenting a possible mechanism by which HTR decreases the risk of cardiovascular disease development during menopause.