Abstract. The aim of the study was to measure the concentrations of plasma homocysteine in premeno pausal and postmenopausal women, and to examine a possible relationship between plasma homocysteine and oestrogen status. Homocysteine metabolism was studied by a standardized oral methionine loading test, and oestrogen status was assessed by the measurement of serum 17/3-oestradiol. Forty-six pre menopausal and 26 postmenopausal healthy women without a history of vascular disease or adverse preg nancy outcome were recruited by public advertise ment. The main outcome measures were the concen trations of fasting and postmethionine plasma homo cysteine, and serum 17/3-oestradiol. Fasting plasma homocysteine concentrations (mean ± SD) were sig nificantly higher in postmenopausal women as coinpared to premenopausal women (12 ± 4 /¿mol L" 1 and 10 ± 3/imol L" 1, respectively) as well as postmethionine plasma homocysteine concentrations (46 ± 16 //mol L-1 and 32 ± 9 /¿mol L ' 1, respec tively). In premenopausal women, postmethionine plasma homocysteine was negatively and significantly correlated to serum 17/3-oestradiol (r = -0-34). It is concluded that plasma homocysteine concentrations, both fasting and after methionine loading, are signifi cantly higher in postmenopausal women than in pre menopausal women. In premenopausal women, the higher concentrations of serum 17/3-oestradiol may account in part for the lower concentrations of post methionine plasma homocysteine.

Objective-The purpose of this study was to investigate whether the effect of transdermal estrogen therapy in postmenopausal women differs from that of oral therapy with regard to resistance to activated protein C (APC), an important risk factor for venous thrombosis, and levels of related proteins, such as protein S, protein C, and prothrombin. Methods and Results-In a randomized, double-blind, placebo-controlled study, 152 healthy hysterectomized postmenopausal women received daily either placebo (nϭ49), transdermal 17␤-estradiol (E 2 ) 50 g (tE 2 group, nϭ33), oral E 2 1 mg (oE 2 group, nϭ37), or oral E 2 1 mg combined with gestodene 25 g (oE 2 ϩG group, nϭ33) for 13 28-day treatment cycles, followed by 4 cycles of placebo for each group. Plasma samples were collected at baseline and in cycles 4, 13, and 17. In cycle 13, significant increases versus baseline and placebo were found in normalized APC sensitivity ratios (nAPCsr) in all treated groups (tE 2 , ϩ26.9%; oE 2 , ϩ102.7%; oE 2 ϩG, ϩ69.9%). Increases in nAPCsr were significantly higher in the oral treatment groups than in the tE 2 group. In addition, compared with baseline and placebo, after 13 cycles, decreases were observed in total protein S (tE 2 , Ϫ4.1%; oE 2 , Ϫ7.9%; oE 2 ϩG, Ϫ5.8%), free protein S (tE 2 , Ϫ7.1%; oE 2 , Ϫ8.4%; oE 2 ϩG, Ϫ5.2%), and protein C in the oE 2 ϩG group (Ϫ6.4%), but these changes did not explain the increase in nAPCsr. Changes in prothrombin were small and also did not affect the nAPCsr. Conclusions-Increases were observed in resistance to APC, which were more pronounced in the oral treatment groups than in the transdermal group. The increase in resistance to APC was not explained by changes in protein S, protein C, or prothrombin and may contribute to the increased incidence of venous thrombosis in users of hormone replacement therapy. Key Words: resistance to activated protein C Ⅲ protein S Ⅲ protein C Ⅲ estrogen replacement therapy Ⅲ venous thrombosis W omen using oral estrogen containing hormone replacement therapy 1-3 or oral contraceptives 4 have an increased risk of developing venous thrombosis. The risk for oral contraceptive users is higher in women who use ethynylestradiol in combination with so-called third-generation progestogens (desogestrel or gestodene) than among women using ethynylestradiol in combination with the secondgeneration progestogen levonorgestrel. 4 This difference might be explained by a differential effect of the progestogens on resistance to activated protein C (APC), 5,6 a risk factor for venous thrombosis. 7,8 It is plausible that the observed increased risk of venous thrombosis in hormone replacement users can also, at least in part, be explained by an increase in resistance to APC.The effect of hormone replacement therapy on resistance to APC, on protein S, and on protein C has been investigated in several studies. However, only few had a randomized, placebo-controlled design. 9 -16 Only uncontrolled 17,18 and cross-sectional 19 studies on the effect of transdermal estradiol on resistance...

SummaryIn this randomised, placebo-controlled 12-week study, sixty healthy postmenopausal women received either placebo (N = 16) or daily 2 mg micronised oestradiol, either unopposed (N = 16, E2 group) or combined with a progestagen for 14 days of each cycle (N = 28, E2+P group).As compared to placebo, plasma levels of AT III were reduced only in the E2 group (∼28%), plasma levels of protein C decreased only in the E2+P group (∼4%) and plasma levels of protein S decreased in both the E2 and E2+P group (∼21%). In both the E2 and E2+P groups, the plasma levels of factor VII (antigen and activity) showed a borderline significant increase (∼10%), whereas no significant change was observed in active factor VII. Plasma levels of tissue-type plasminogen activator (∼22%), urokinase plasminogen activator (∼25%) and plasminogen activator inhibitor type-1 (∼43%) decreased in the E2 and E2+P groups, whereas those of plasminogen increased (∼12%). Treatment was associated with an increase in levels of prothrombin fragment 1+2 (∼31%), but levels of thrombin-antithrombin III complexes, and of plasmin-α2-antiplasmin complexes and total fibrin(ogen) degradation products did not change significantly.Short-term E2 and E2+P treatment is associated with a shift in the procoagulant-anticoagulant balance towards a procoagulant state. A substantial proportion of women do not have a net increase in fibrinolytic activity. These data may be relevant in explaining the increased risk of venous thromboembolism associated with ERT and HRT, and possibly also in explaining the negative results of the Heart and Estrogen/progestin Replacement Study.

Summary Objective: To study the short-term effect of unopposed oestradiol (E2) and sequentially combined hormone replacement therapy (E2 + P) on C-reactive protein (CRP) in healthy postmenopausal women. Design: Prospective, randomised, placebo-controlled 12-week study. Sixty healthy, normotensive, non-hysterectomised postmenopausal women received either placebo (N = 16) or daily 2 mg micronised oestradiol, either unopposed (N = 16, E2 group) or sequentially combined with a progestagen on 14 days of each cycle (N = 28, E2+P group). Data were collected at baseline and at 4 and 12 weeks. Results: CRP levels increased significantly during the 12 weeks in the E2 and the E2+P groups compared to placebo. No differences were found between the E2 group and the E2+P group [E2 and E2+P group together (N = 44) versus placebo: P = 0.01; E2 versus E2+P: P = 0.75]. To give a quantitative estimate of the increase, the median change calculated from baseline in both treatment groups together was +87% (P = 0.02) at 4 weeks, and +114% (P = 0.08) at 12 weeks, as compared to the placebo group. Conclusion: In healthy postmenopausal women, short-term treatment with E2 or E2+P was associated with a rapid rise in CRP concentrations. These observations raise the possibility that the increased risk of cardiovascular events is related to an initial increase in CRP levels after starting hormone replacement therapy.

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Plasma fasting homocysteine concentrations are lowered by E2-dydrogesterone therapy in postmenopausal women.

In a prospective, randomized, placebo-controlled 12-wk study, we investigated the effect of oral hormone replacement therapy on asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), and an independent risk factor for coronary heart disease. The effects on arginine and symmetric dimethylarginine were also investigated. Sixty healthy early postmenopausal women received daily placebo (n = 16) or oral 17beta-estradiol 2 mg, either unopposed (E(2); n = 16) or sequentially combined with dydrogesterone 10 mg (E(2)+D; n = 14) or trimegestone 0.5 mg (E(2)+T; n = 14). ADMA levels reduced in all active treatment groups. Compared with baseline and placebo, the largest reduction in ADMA levels was observed in the E(2)+T group [-18.7% (95% confidence interval [CI], -25.4 to -11.9%) and -21.1% (95% CI, -26.2 to -16.1%), at 4 and 12 wk, respectively]. At 4 and 12 wk in the E(2)+T group, arginine levels were significantly reduced as well [-30.9% (95% CI, -41.1 to -20.7%) and -36.3% (95% CI, -43.1 to -29.5%), respectively], whereas symmetric dimethylarginine levels were significantly lower in the E(2)+D group after 12 wk [-11.6% (95% CI, -19.9 to -3.3%)]. In conclusion, unopposed oral estradiol and estradiol combined with dydrogesterone or trimegestone reduced plasma levels of the NOS inhibitor ADMA. Whether the reduction of the NOS substrate arginine in the E(2)+T group counteracts the potentially beneficial effect of ADMA reduction or reflects increased NO production remains to be investigated.