Effects of low-dose oral and transdermal estrogen replacement therapy on hemostatic factors in healthy postmenopausal women: a randomized placebo-controlled study.

OBJECTIVE: This study was undertaken to investigate the effect of transdermal and oral estrogen replacement therapy in healthy postmenopausal women on markers of coagulation and fibrinolysis associated with coronary artery disease.

STUDY DESIGN: In a randomized, placebo-controlled, double-blind study, healthy hysterectomized postmenopausal women received daily either placebo (n=49), transdermal 17beta-estradiol (E(2)) 50 microg (tE(2) group, n=33), oral E(2) 1 mg (oE(2) group, n=37), or oral E(2) 1 mg combined with gestodene 25 microg (oE(2)+G group, n=33) for thirteen 28-day treatment cycles. Hemostatic variables were measured in blood samples collected at baseline and in cycles 4 and 13.

RESULTS: No significant changes versus baseline and placebo were found in the tE(2) group, except for plasminogen activator inhibitor type-1 (PAI-1) in cycle 13 (-32.4%, P=.01). In the oE(2) group, significant percentage changes from baseline versus placebo in cycle 13 were found in fibrinogen, -5.4% (P<.05); factor VII, -7.3% (P<.05); thrombin-antithrombin III complexes, -13.3% (P<.05); tissue-type plasminogen activator (t-PA), -17.3% (P<.001); and PAI-1, -54.3% (P<.001). In the oE(2)+G group, respective changes were factor VII, -17.6% (P<.001); t-PA, -14.5% (P=.01); PAI-1, -36.4% (P<.01); and D-dimer, +21.8% (P<.05). No significant changes were observed in prothrombin fragment 1+2 and plasmin-alpha(2)-antiplasmin complexes.

CONCLUSION: Low-dose oral estradiol therapy was associated with an increase in fibrinolysis and small decreases in procoagulant variables. Transdermal therapy had minor effects.