Oestrogen--progestin therapy and the lipid balance of post-menopausal women

The effect of hormone replacement therapy on the levels of serum lipids, apolipoprotein AI, apolipoprotein B and lipoprotein (a) in Turkish postmenopausal women

OBJECTIVES

Estrogen replacement therapy alters the lipid profiles favorably for delaying atherosclerosis in postmenopausal women. The effects of estrogen plus progesterone combination therapy on lipids are controversial. This study was designed to evaluate the effect of female sex hormones on lipids and lipoproteins and to clarify the influence of progesterone on the effect of estrogen in postmenopausal women.

METHODS

Of the 60 postmenopausal women admitted to our menopause clinic, 40 had intact uterus and received continuous 0.625 mg conjugated equine estrogen (CEE) plus 2.5 mg medroxyprogesterone acetate (MPA), whereas the remaining 20 were hysterectomized and received 0.625 mg CEE daily. To assess the alterations in lipids and lipoproteins during menopause, 45 healthy premenopausal women were investigated. Lipid and lipoprotein levels were assessed in each subject at baseline and at the 6th and 18th months of therapy.

RESULTS

In menopause, a shift towards more atherogenic lipid and lipoprotein profiles than those of the premenopausal state was found. Following 18 months of treatment, both regimens reduced total cholesterol (TC) levels as compared with the baseline (6.4 vs. 6.9% in the CEE/MPA and CEE groups, respectively). The CEE group had a more pronounced increase in high-density lipoprotein (HDL) cholesterol than the CEE/MPA group (10.3 vs. 8.8%, respectively). Both groups displayed reduced TC, low-density lipoprotein (LDL) cholesterol and apolipoprotein-B (ApoB) concentrations, whereas triglycerides increased, with a greater tendency to increase in the CEE/MPA group at the end of the trial. Also, the lipoprotein (a) [Lp(a)] levels decreased significantly (27.6 vs. 24.5% in the CEE/MPA and CEE groups, respectively). This decrease was more pronounced in subjects with a relatively higher basal Lp(a) concentration.

CONCLUSION

Both treatment regimens caused positive alterations in the lipid and lipoprotein profiles. This association might play a pivotal role in the postmenopausal increases in atherosclerotic diseases and cardioprotective effect of estrogen in postmenopausal women.

Effect of conjugated equine estrogen in combination with two different progestogens on the risk factors of coronary heart disease in postmenopausal Chinese women in Taiwan: a randomized one-year study

BACKGROUND

To compare the effect of hormone replacement therapy (HRT) using estrogen plus dydrogesterone or estrogen plus medroxyprogesterone acetate (MPA) on the risk factors for coronary heart disease (CHD) in postmenopausal women.

METHODS

A randomized, prospective 1-year clinical trial was designed. All of the postmenopausal women (n = 279) received sequential conjugated equine estrogen (CEE) at a dose of 0.625 mg/day for 25 days (days 1-25) of each month. These women were also randomly assigned to receive either dydrogesterone 10 mg/day (E + D group, n = 140) or MPA 5 mg/day (E + P group, n = 139) for 14 days (days 12-25) of each month. Serum biochemical markers, lipoproteins, plasma prothrombin time (PT), partial prothrombin time (PPT) and antithrombin III-antigen (ATIII-Ag) were analyzed at baseline, and after 6 and 12 months of treatment.

RESULTS

Liver function, renal function, PT and PPT did not change significantly during the 12-month trial. The E + D group had a more pronounced increase in high density lipoprotein cholesterol (HDL-C) than the E + P group (10.6% vs. 2.7%) after 12 months of treatment (p < 0.05). Both groups showed reduced concentrations of total cholesterol (T-CHO), low density lipoprotein cholesterol (LDL-C) and ATIII, whereas triglyceride (TG) was increased at the end of the trial (without intergroup difference).

CONCLUSIONS

Our study demonstrated a favorable effect on lipoprotein profiles with both hormone replacement therapy regimens. Dydrogesterone appears to be superior to medroxyprogesterone acetate from the perspective of modification of coronary heart disease risk factors.

Effects of postmenopausal hormone replacement therapy on lipid, lipoprotein, and apolipoprotein (a) concentrations: analysis of studies published from 1974-2000

OBJECTIVE

To establish reference estimates of the effects of different hormone replacement therapy (HRT) regimens on lipid and lipoprotein levels.

DESIGN

Review and pooled analysis of prospective studies published up until the year 2000.

SETTING

Clinical trials centers, hospitals, menopause clinics.

PATIENT(S)

Healthy postmenopausal women.

INTERVENTION(S)

Estrogen alone, estrogen plus progestogen, tibolone, or raloxifene in the treatment of menopausal symptoms.

MAIN OUTCOME MEASURE(S)

Serum high- and low-density lipoprotein (HDL and LDL) cholesterol, total cholesterol, triglycerides, and lipoprotein (a).

RESULT(S)

Two-hundred forty-eight studies provided information on the effects of 42 different HRT regimens. All estrogen alone regimens raised HDL cholesterol and lowered LDL and total cholesterol. Oral estrogens raised triglycerides. Transdermal estradiol 17-beta lowered triglycerides. Progestogens had little effect on estrogen-induced reductions in LDL and total cholesterol. Estrogen-induced increases in HDL and triglycerides were opposed according to type of progestogen, in the order from least to greatest effect: dydrogesterone and medrogestone, progesterone, cyproterone acetate, medroxyprogesterone acetate, transdermal norethindrone acetate, norgestrel, and oral norethindrone acetate. Tibolone decreased HDL cholesterol and triglyceride levels. Raloxifene reduced LDL cholesterol levels. In 41 studies of 20 different formulations, HRT generally lowered lipoprotein (a).

CONCLUSION(S)

Route of estrogen administration and type of progestogen determined differential effects of HRT on lipid and lipoprotein levels. Future work will focus on the interpretation of the clinical significance of these changes.

Transdermal estrogen replacement therapy and plasma lipids in 693 French women

OBJECTIVES

The cardiovascular effects of transdermal estrogen are not so well established than those induced by oral estrogen. In a representative sample of French postmenopausal women, we assessed plasma lipid changes induced by transdermal 17 beta-estradiol.

METHODS

This cross-sectional study was carried out among the population sample of the third MONICA survey on cardiovascular risk factors. We selected 693 postmenopausal women according to the followed criteria; women with intact uterus and no menstruation for more than 12 months, women with bilateral oophorectomy, hysterectomized women older than 55 years and hysterectomized women who had followed hormone replacement therapy. We used multivariate linear regression models, taking into account confounding variables, to assess lipid changes induced by estrogen.

RESULTS

We compared 192 women currently taking transdermal 17 beta-estradiol (27 unopposed estrogen and 165 estrogen plus progestin) with 501 women without any hormonal treatment. After adjustment for living area, education level, income tax, smoking, alcohol consumption, physical activity, age and body mass index, transdermal estrogen replacement therapy (ERT) was significantly associated with lower levels of serum total cholesterol [6.10 (S.E., 0.11) vs 6.35 (0.09) mmol/l, P < 0.01], triglycerides [1.06 (0.06) vs 1.23 (0.05) mmol/l, P < 0.001], LDL-cholesterol [3.93 (0.11) vs 4.13 (0.09) mmol/l, P < 0.05], VLDL-cholesterol [0.48 (0.03) vs 0.56 (0.02) mmol/l, P < 0.001] and apolipoprotein B [1.20 (0.03) vs 1.26 (0.02) g/l, P < 0.01]. Levels did not differ significantly for HDL-cholesterol [1.68 (0.05) vs 1.66 (0.04) mmol/l] and apolipoprotein A1 [1.79 (0.03) vs 1.81 (0.02) g/l].

CONCLUSION

Transdermal ERT may confer a cardiovascular protection by lowering atherogenic lipoproteins.

Effect of progestogens on estrogen-induced lipoprotein changes

A study was performed to evaluate the role of progestogens, on estrogen-induced changes in lipoprotein levels. Sixty postmenopausal symptomatic women, aged 36-59, were included in the study. They were prospectively randomized to a sequential schedule (n = 20), 17 beta-estradiol transdermally 0.05 mg/day on days 1-24 and medroxyprogesterone acetate 10 mg/day orally on days 15-24 or a continuous schedule (n = 20), 17 beta-estradiol transdermally 0.05 mg/day and medroxyprogesterone acetate 2.5 mg/day orally on days 1-24. Patients who had total abdominal hysterectomy+bilateral salphingooopherectomy (n = 20) received only 17 beta-estradiol 0.05 mg/day continuously. Serum total cholesterol (TC), high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol and triglyceride (TG) levels were determined prior to and at the 3rd, 6th and 9th month of therapy in all groups. Mean TC, TG and LDL cholesterol levels did not change significantly during therapy (P > 0.05). Only the mean HDL cholesterol levels showed significant increases in all groups; from 42.30 +/- 9.97 mg/dl to 64.10 +/- 6.81 mg/dl in group I (P < 0.001), from 41.85 +/- 9.09 mg/dl to 60.65 +/- 7.41 mg/dl in group II (P < 0.001) and from 40.70 +/- 11.26 mg/dl to 58.80 +/- 7.74 mg/dl in group III (P < 0.001). It is concluded that medroxyprogesterone acetate, whether used continuously or sequentially, does not oppose the beneficial effects of transdermal 17 beta-estradiol on the lipoprotein profile.

Effects of sex steroids on serum lipids and lipoproteins

Cardiovascular disease is the leading cause of death in women but manifests itself primarily in the postmenopausal years. Menopause appears to increase the cardiovascular risk, at least when surgically induced, whereas the effects of the natural menopause are still a matter of debate. Why postmenopausal women apparently lose their natural cardioprotection is not established, but oestrogen deficiency seems to play an important role. Loss of ovarian hormone production at the menopause significantly alters serum lipids and lipoproteins, giving rise to more atherogenic lipid profiles throughout the postmenopausal years, and these changes may in part be responsible for the alleged cardiovascular risk. Postmenopausal hormone replacement therapy, using oral unopposed oestrogens, induces potential favourable effects on lipids and lipoproteins, and epidemiological evidence has established that the risk of cardiovascular mortality is reduced by 40-60% in women receiving postmenopausal oestrogen therapy. Part of this reduction seems to be explained by changes in lipids and lipoproteins. Parenteral administration of oestrogens induces comparable, although less pronounced effects on lipids and lipoproteins, and the possible cardioprotective role of parenteral administration remains obscure. The addition of progestogens to postmenopausal oestrogen therapy is essential for endometrial protection, but progestogens apparently antagonize some of the actions of oestrogens on lipid metabolism. However, the type, the dose, the duration and the route of administration, as well as the potency balance between the oestrogen and the progestogen employed, are important determinants for the ultimate effect on lipid metabolism. With the use of cyclic administration and the lowest possible doses of progestogens, the oestrogenic actions on lipids and lipoproteins can be largely preserved, but the cardioprotective potential of combined oestrogen-progestogen therapy is as yet unknown.

Benefits and risks of menopausal estrogen and/or progestin hormone use

Current evidence is reviewed here on risks and benefits of estrogen and progestin use by peri- and postmenopausal women in relation to the following conditions: endometrial cancer, breast cancer, osteoporosis, and coronary artery disease (CAD). On balance, estrogen therapy appears to be beneficial for menopausal women, as it probably reduces the risks of CAD and osteoporosis, two of the major causes of mortality and morbidity. Although unopposed estrogen therapy increases the risk of endometrial cancer, that cancer is relatively rare and is not fatal in the vast majority of cases associated with estrogen use. Definitive conclusions about the relation of menopausal estrogens to breast cancer cannot be drawn due to inconsistent evidence to date. Although evidence from randomized controlled trials is lacking, biochemical and clinical evidence suggest that progestin supplementation is associated with a reduction in endometrial cancer risk in women taking menopausal estrogens. Progestin supplementation also may augment the beneficial effects of estrogens in providing protection against osteoporosis, although this effect is not yet well established. There is little direct evidence bearing on the relation of menopausal progestins to breast cancer. Although studies of CAD per se are lacking at present, progestins probably unfavorably alter lipoprotein profiles, thereby increasing a user's risk of CAD. Given the relatively high incidence and mortality of CAD in postmenopausal women, any negative effects on CAD risk could potentially counterbalance beneficial effects on other causes. We conclude that estrogen replacement therapy is of potential benefit to postmenopausal women, but that the question of progestin supplementation requires further study, particularly for CAD risk.

Dose and duration effects of oestradiol valerate on serum apolipoproteins A1 and B

The serum levels of apolipoprotein A1 (ApoA1) and apolipoprotein B (ApoB) were assessed by electroimmunoassay in 19 bilaterally oophorectomised women before and after treatment with 2 and 4 mg oestradiol valerate (E2V) daily. The first part of the study was conducted in accordance with an open cross-over design. The levels of ApoA1 were found to have increased after the 6-week treatment periods using each of those dosages, the increase being most pronounced after treatment with 4 mg E2V. ApoB concentrations decreased at both dosage levels. The serum levels of total (TC) and free cholesterol (FC) and phospholipids (PL) in the high-density lipoprotein (HDL) fraction correlated positively with the serum levels of ApoA1 before treatment. The correlations between serum ApoA1 and HDL-PL levels persisted after both dosage regimens. Before and after treatment with 2 mg E2V, serum ApoB levels correlated positively with the levels of all lipid components in the low-density lipoprotein (LDL) fraction. After 4 mg E2V, serum ApoB levels correlated positively with LDL-PL and LDL-TC levels. On conclusion of the cross-over, in order to assess the effects of the duration of therapy, the women were followed up for a further period of 3 mth, during which ten were given 2 mg and the other nine 4 mg of E2V daily. The increased levels of ApoA1 and the decreased levels of ApoB seen after the cross-over study were not found to have altered after this treatment-duration evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)