National differences in lipid response to postmenopausal hormone replacement therapy

Effects of intranasal estradiol treatment on serum paraoxonase and lipids in healthy, postmenopausal women

BACKGROUND/AIMS

Serum lipid concentrations worsen after the menopause because of estrogen deficiency, leading to an increased atherogenic pattern. It is known that serum paraoxonase (PON1) activity prevents the development of atherosclerosis. The aim of this cross-sectional study was to observe the effects of intranasal 17beta-estradiol (300 microg/day) on serum PON1 and lipid levels in healthy postmenopausal women.

METHODS

48 healthy, postmenopausal women were enrolled into this cross-sectional study. 28 subjects without an intact uterus and ovaries were using single-dose (300 microg/day) intranasal 17beta-estradiol and 20 subjects with spontaneous natural menopause were not on any hormone therapy. Body mass index (BMI), blood pressure, serum follicle-stimulating hormone, estradiol, fasting glucose, insulin, lipid fractions and PON1 levels were measured. Homeostasis model assessment (HOMA-R) was used to estimate insulin resistance.

RESULTS

The higher estradiol, high-density lipoprotein and salt-stimulated paraoxonase (SSP) levels were observed in intranasal 17beta-estradiol users in comparison with non-users. There were no statistically significant differences in BMI, blood pressures, other lipid fractions, basal paraoxonase, arylesterase, fasting glucose and insulin levels, HOMA-R between the groups. SSP was inversely associated with fasting insulin levels and HOMA-R.

CONCLUSION

These observations may suggest that intranasal 17beta-estradiol does not have harmful effects on the PON1 activity and lipid metabolism.

Effects of Transdermal Estrogen Replacement Therapy on Cardiovascular Risk Factors

The prevalence of hypertension and cardiovascular disease increases dramatically after menopause in women, implicating estrogen as having a protective role in the cardiovascular system. However, recent large clinical trials have failed to show cardiovascular benefit, and have even demonstrated possible harmful effects, of opposed and unopposed estrogen in postmenopausal women. While these findings have led to a revision of guidelines such that they discourage the use of estrogen for primary or secondary prevention of heart disease in postmenopausal women, many investigators have attributed the negative results in clinical trials to several flaws in study design, including the older age of study participants and the initiation of estrogen late after menopause.Because almost all clinical trials use oral estrogen as the primary form of hormone supplementation, another question that has arisen is the importance of the route of estrogen administration with regards to the cardiovascular outcomes. During oral estrogen administration, the concentration of estradiol in the liver sinusoids is four to five times higher than that in the systemic circulation. This supraphysiologic concentration of estrogen in the liver can modulate the expression of many hepatic-derived proteins, which are not observed in premenopausal women. In contrast, transdermal estrogen delivers the hormone directly into the systemic circulation and, thus, avoids the first-pass hepatic effect.Although oral estrogen exerts a more favorable influence than transdermal estrogen on traditional cardiovascular risk factors such as high- and low-density lipoprotein-cholesterol levels, recent studies have indicated that oral estrogen adversely influences many emerging risk factors in ways that are not seen with transdermal estrogen. Oral estrogen significantly increases levels of acute-phase proteins such as C-reactive protein and serum amyloid A; procoagulant factors such as prothrombin fragments 1+2; and several key enzymes involved in plaque disruption, while transdermal estrogen does not have these adverse effects.Whether the advantages of transdermal estrogen with regards to these risk factors will translate into improved clinical outcomes remains to be determined. Two ongoing clinical trials, KEEPS (Kronos Early Estrogen Prevention Study) and ELITE (Early versus Late Intervention Trial with Estradiol) are likely to provide invaluable information regarding the role of oral versus transdermal estrogen in younger postmenopausal women.

Effects of continuous combined conjugated estrogen/medroxyprogesterone acetate and 17β-estadiol/norethisterone acetate on lipids and lipoproteins

OBJECTIVES

Various estrogen/progestogen combinations used in hormonal replacement therapy (HRT) have been reported to influence lipid and lipoprotein fractions differently. This motivated a comparative study where the two continuous combined regimens most commonly used in Sweden during the 1990s have been studied regarding effects on lipid profile.

METHODS

In a 1-year prospective, double-blind study, 62 post-menopausal women were randomized to conjugated estrogen (CE), 0.625 mg, and medroxyprogesterone acetate (MPA), 5 mg, or 17beta-estradiol (E2), 2 mg, and norethisterone acetate (NETA), 1 mg. Serum concentrations of lipids and lipoproteins were measured at baseline and after 1 year of treatment.

RESULTS

Both treatment groups significantly lowered the lipoprotein(a) (Lp(a)) levels. The CE/MPA group showed no significant changes in total cholesterol (TC), high-density (HDL) and low-density lipoprotein (LDL), but a significant increase of triglyceride (TG) levels. The E2/NETA group developed a significant lowering of total cholesterol, HDL, and LDL, but no significant changes of TG levels. The magnitude of change in serum concentrations of total cholesterol, HDL and TG differed significantly between the two treatment groups.

CONCLUSIONS

Continuous combined treatment with CE/MPA and E2/NETA equally lowered Lp(a), an important risk factor for cardiovascular disease in women. Apart from this, the two treatments produced different effects on lipids and lipoproteins, findings that are more delicate to interpret.

The short-term effects of different regimens of hormone replacement therapy on left ventricular structure and performance in healthy postmenopausal women. A prospective, controlled echocardiographic study

OBJECTIVE

To compare the short-term effects of different hormone replacement therapy (HRT) regimens on left ventricular structure and function in healthy postmenopausal women.

METHODS

Forty-two apparently healthy postmenopausal women were evaluated prospectively in this controlled study. Subjects were divided into 4 groups. Ten subjects, who did not accept HRT or any other treatments, formed the control group. The remaining subjects were assigned to receive oral estradiol (2 mg/day) + norethisterone acetate (1 mg/day) (n = 11), transdermal estradiol (0.05 mg) + norethisterone acetate (0.25 mg) (n = 11) or tibolone (2.5 mg/day) (n = 10) therapy during 12 weeks. Echocardiography and Doppler techniques were used to assess the cardiac effects of different HRT regimens.

RESULTS

After 12 weeks of treatment, there were significant increases in left ventricular ejection fraction (transdermal group: p = 0.008, oral group: p = 0.003, tibolone group: p = 0.005) and cardiac output (transdermal group: p = 0.003, oral group: p = 0.003, tibolone group: p = 0.021) in all treatment groups. In addition, in the transdermal group, a slight increase in left ventricular end-diastolic volume was significant (p = 0.046).

CONCLUSION

These data suggest that oral and transdermal HRT regimens and tibolone may contribute to the improvement in left ventricular systolic function without having an effect on left ventricular structure after short-term administration in healthy postmenopausal women.

Dietary fish oil decreases C-reactive protein, interleukin-6, and triacylglycerol to HDL-cholesterol ratio in postmenopausal women on HRT

BACKGROUND

Atherogenesis is a complex process involving both a low-grade inflammation and a disturbed lipid profile. Although dietary fish and fish oil improve the latter of these two risk factors, their impact on the former is less clear.

OBJECTIVE

This study addressed the effect of supplementation with fish oil in doses achievable with diet on serum C-reactive protein (CRP), interleukin-6 (IL-6), and the lipid profile.

METHODS AND RESULTS

Thirty healthy subjects taking HRT were randomly divided into three groups and supplemented for five weeks with 14 g/day safflower oil (SO), 7 g/day of both safflower oil and fish oil (LFO), or 14 g/day fish oil (HFO). Measurements included serum high-sensitivity CRP, IL-6 in plasma and in cell culture supernatant collected from 24-hr lipopolysaccharide (LPS)-stimulated whole blood, and lipid profile markers. CRP and IL-6 were adjusted for body mass index (BMI). Fish oil supplementation significantly decreased CRP and IL-6 compared to SO, with a greater effect in the LFO than HFO groups. Plasma triacylglycerol (TG) and the TG/HDL-C ratio were significantly lower in the HFO compared to the SO group.

CONCLUSIONS

These results suggest that dietary fish oil may decrease the risk for cardiovascular disease through the modulation of both plasma lipids and inflammatory markers in healthy postmenopausal women.