Objective: To study a possible use of sex hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG) as markers for changes in hemostatic factors during oral postmenopausal hormone replacement therapy (HRT).
Methods: Twenty-eight postmenopausal women were treated with oral conjugated equine estrogens+oral medroxyprogesterone acetate (CEE + MPA, n = 15) or with placebo (n = 13). Serum SHBG, CBG, testosterone, cortisol and plasma coagulation factors, coagulation inhibitors and markers of coagulation activation were measured before and after 6 and 12 months of treatment.
Results: Pretreatment plasminogen activator inhibitor 1 (PAI-1) levels correlated negatively to SHBG and antithrombin III (AT III) negatively to total and free cortisol. In the CEE + MPA group, CBG, SHBG and Factor VII increased, and PAI-1, AT III and free testosterone decreased during treatment. No significant changes were found in plasma von Willebrand factor antigen, thrombin-antithrombin complex, fibrin D-dimer and fibrinogen. A significant, negative correlation was found between changes in SHBG and PAI-1. No changes were found in the placebo group.
Conclusion: The only correlation found between changes in "steroid sensitive" proteins and hemostatic factors was between increased SHBG and a possibly beneficial effect of estrogens, i.e. decreased PAI-1 values. SHBG or CBG could not be used as predictors of increased cardiovascular risk during postmenopausal oral HRT.