Changes in hemostatic parameters after oral hormone therapy in postmenopausal women

Oral hormone therapy (HT) and menopausal age are both prothrombotic risk factors. The aim of our study was to compare the hemostatic parameters in plasma of postmenopausal women after 6 months of oral HT with parameters of control (without treatment) postmenopausal women.

Twenty-seven postmenopausal women were treated with 17β-estradiol (1 mg) and dydrogesterone (5 mg) daily for 6 months. The control group (27 women) did not receive any HT. Hemostatic factors, such as fibrinogen (FG) concentration, activated partial thromboplastin time (APTT), platelet (PLT) count, maximum velocity of clot formation, and fibrin lysis half-time were estimated.

The hemostatic parameters in both groups differ significantly. After 6 months oral HT, APTT and the level of FG were higher than in the control group (APTT 30.08 seconds vs. 28.18 seconds, p = 0.02; FG 4.14 g/L vs. 3.03 g/L, p < 0.001). However, the higher values of maximal velocity of FG polymerization (153.53 mOD/min vs. 92.87 mOD/min, p < 0.001), maximum absorbance values (0.306 vs. 0.275, p < 0.001), and fibrin lysis half-time (32.33 minutes vs. 18.11 minutes, p < 0.001) compared with values in the control group also were observed. There was no statistically significant difference in PLT counts between control and women treated with oral HT.

Six months of oral combined HT (17β-estradiol and dydrogesterone) caused increased initial velocity of clot formation and inhibition of fibrinolysis. The increased level of FG and its higher polymerization may help explain the increase in venous thrombosis and cardiovascular events reported after the use of oral HT.