Influence of menopause on serum lipids and lipoproteins

Reproductive history and cardiovascular disease risk in postmenopausal women: a review of the literature

OBJECTIVES

It is widely believed that oestrogen protects postmenopausal women from cardiovascular disease. It is unknown, however, whether reproductive history, which affects endogenous oestrogen levels during a woman's life, also influences cardiovascular disease risk in postmenopausal women. We present an overview of the studies which investigate the relationship between reproductive history and risk for cardiovascular disease in women.

METHODS

We conducted a Medline search of literature pertaining to age at menarche, age at menopause, parity and gravidity, breast-feeding, and length and regularity of the menstrual cycle in relation to cardiovascular diseases. Data extraction and synthesis were performed by comparing odds ratios and relative risks presented or calculated.

RESULTS

Age at menarche was not found to influence cardiovascular disease risk, while menstrual cycle irregularity was associated with this risk. The studies pertaining to parity presented conflicting results: protection against as well as an increase in the risk of cardiovascular disease were found in parous women. Pregnancy loss appeared to be related to cardiovascular disease risk. Age at menopause proved to be the reproductive factor most clearly related to cardiovascular disease risk.

CONCLUSIONS

Only menstrual cycle irregularity, pregnancy losses, and age at menopause are possibly related to cardiovascular disease risk in postmenopausal women. All reproductive factors need to be studied together in order to assess reproductive history in a proper manner. Research of this kind will be essential if we are to further increase our knowledge regarding the nature of the effects of endogenous oestrogen on cardiovascular disease.

Is the response of serum lipids and lipoproteins to postmenopausal hormone replacement therapy modified by ApoE genotype?

Postmenopausal hormone replacement therapy (HRT) has favorable effects on the serum lipid profile, and it also decreases the risk of cardiovascular diseases. The apolipoprotein E genotype has influence on serum levels of lipids and lipoproteins; apoE allele epsilon4 (apoE4) is associated with high total and LDL cholesterol levels. Genotype also influences the lipid responses to treatment with diet and statins, but the effect of HRT in different apoE genotypes is unknown. We studied the effects of HRT on the concentrations of serum lipids in apoE4-positive early postmenopausal women (genotypes 3/4 and 4/4) compared with apoE4-negative women (genotypes 2/3 and 3/3) in a population-based, prospective 5-year study. In all, 232 early postmenopausal women were randomized into 2 treatment groups: an HRT group (n=116), which received a sequential combination of 2 mg estradiol valerate (E2Val) from day 1 to 21 and 1 mg cyproterone acetate (CPA) from day 12 to 21 (Climen), and a placebo group (n=116), which received 500 mg/d calcium lactate. Serum concentrations of total, LDL, and HDL cholesterol and triglycerides were measured at baseline and after 2 and 5 years of treatment. A total of 154 women completed the final analysis. During the follow-up period, serum total cholesterol and LDL cholesterol concentrations decreased in the HRT group in apoE4-negative women (8.1% and 17.1%, respectively; P<0.001) but did not change in the HRT group in apoE4-positive women or in the placebo group. Serum HDL cholesterol concentrations decreased in the placebo group (apoE4-negative, 3.9%, P=0.015; apoE4-positive, 8.1%, P=0.004) but did not change significantly in the HRT group. Serum triglyceride levels tended to increase in both study groups and genotypes (15.1% to 36.2%, P<0.038 to 0.001), but no differences were observed between the study groups or genotypes, respectively. Our finding was that in postmenopausal Finnish women LDL cholesterol levels in apoE4-negative subjects respond more favorably to HRT than those in apoE4-positive subjects. This finding has potential importance in postmenopausal women with hypercholesterolemia, if confirmed in other studies.

Coronary heart disease risk factors and menopause: a study in 1684 French women

This study aimed to assess the relationship between menopause and various risk factors for coronary heart diseases (CHD) in a large sample of French women aged 45 65 years. One thousand six hundred and eighty-four consecutive healthy women who received a systematic check-up in our Menopause Unit were included in this study. All the women answered a computer-assisted questionnaire which comprised 156 items, 72 questions being exclusively related to the identification of familial and personal cardio-vascular risk factors. Biological measurements were performed to evaluate lipid-lipoprotein profile and fasting glucose levels. Women, none of whom were treated with hormonal replacement therapy, were classified as postmenopausal according to the date of their last menses and levels of serum FSH and estradiol (n = 1200). Perimenopausal women were further subdivided into two subgroups according to the regularity of their menstrual cycles and FSH levels (early (n = 143) and late (n = 341) perimenopause). 12% (n = 205) of the women were currently receiving lipid-lowering drugs (84.4% postmenopausal vs. 15.6% perimenopausal). When all women were considered, menopause was associated with a higher prevalence of hypertension and hypercholesterolemia (serum total cholesterol level > 250 mg/dl + LDL cholesterol level > 160 mg/dl). This higher prevalence in postmenopausal women was also found when the analysis was restricted to women aged 45 55 years, which rather suggests an effect of menopause than of age. Of the women not receiving hypolipidemic treatments, postmenopausal women had significantly higher serum levels of total cholesterol, LDL , VLDL cholesterol, triglycerides and apolipoprotein B and lower levels of HDL cholesterol than perimenopausal women. Multivariate analysis indicated that these effects were independent of age, body mass index and years since menopause. The prevalence of other metabolic disturbances was much more lower. On average, perimenopausal women had significantly less CHD risk factors than postmenopausal women (P < 0.0001). Fifty-two per cent of the perimenopausal women had none of the risk factors studied as compared with 39% of the postmenopausal women (P < 0.0001). This study shows that menopause was associated with a higher prevalence of risk factors for CHD.

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.

Effects of oral combined hormone replacement therapy on plasma lipids and lipoproteins

Hormone replacement therapy has been shown to decrease the risk of coronary heart disease (CHD) in menopausal women. In this cross-sectional study, we addressed the following question: What effects would combined oral hormone replacement therapy have on plasma lipid and lipoprotein profiles independent of the other known CHD risk factors? We analyzed the plasma lipoproteins of two groups of menopausal women who were randomly selected from a large database of individuals. One group (n = 10) was not taking any hormone replacement therapy (NO HRT), while the second group (n = 8) was taking a daily dose of 0.625 mg conjugated estrogen and 2.5 mg medroxyprogesterone orally (PremPro, Wyeth-Ayerst, Philadelphia, PA) for at least 6 months (HRT). The two groups were not different in age, body weight, percent body fat, body mass index (BMI), waist to hip ratio, blood pressure, or insulin and glucose levels. High-density lipoprotein (HDL)-cholesterol was significantly higher (P < .05) in the HRT group. The total cholesterol (TC) to HDL-cholesterol ratio was significantly lower for HRT versus NO HRT (P < .05). Apolipoprotein (apo) A-1, the apo A-1/B ratio, and lecithin:cholesterol acyltransferase (LCAT) activity were significantly higher in HRT (P < .05). Lipoprotein subclass profiles measured by nuclear magnetic resonance (NMR) spectroscopy showed an increase in larger HDL subpopulations (H3 and H4) in HRT (P < .05), which are considered antiatherogenic. No differences were seen in the cholesterol concentration or size of low-density lipoprotein (LDL) subpopulations in HRT compared with NO HRT. These results indicate that the combined estrogen and progesterone treatment leads to beneficial effects on plasma lipoproteins. The beneficial effects include (1) increases in HDL-cholesterol and predominance of HDL2, (2) no adverse effects on LDL subpopulation distribution, and (3) increases in apo A-1 levels and LCAT activity, which indicate an improvement in reverse cholesterol transport.

Cardiorespiratory fitness and cardiovascular disease risk factors in postmenopausal women

PURPOSE

The purpose of the present study was to determine if individuals with high levels of cardiorespiratory fitness have better levels of the cardiovascular disease (CVD) risk factors of total cholesterol (TC), HDL cholesterol (HDL), total cholesterol/HDL cholesterol ratio (TC/HDL), triglycerides (TG), and fibrinogen (FIB) when compared with those with low fitness, in 283 nonsmoking, postmenopausal women. Second, we examined the relation between fitness and CVD risk after controlling for use of hormones and other possible confounding factors.

METHODS

These analyses were done on a subset of nonsmoking, postmenopausal women in the Aerobics Center Longitudinal Study (ACLS). Records of postmenopausal women who completed a preventive medicine physical examination between 1987 and 1995 were examined. Cardiorespiratory fitness level was determined by total treadmill time to exhaustion on a graded exercise test; CVD risk factors were assessed via blood analysis.

RESULTS

On cross-sectional regression analysis, fitness was significantly associated (P < or = 0.005) with TC (r2 = 0.08), TC/HDL (r2 = 0.12), TG (r2 = 0.09), and FIB (r2 = 0.06), and an increase in HDL (r2 = 0.04). After controlling for hormone status, age, year of testing, and blood glucose, each outcome variable remained significantly associated with cardiorespiratory fitness (P < 0.05). TC/HDL and TG continued to be significantly related to cardiorespiratory fitness after adjusting for body mass index (BMI) as a control variable (P < 0.01). The lack of significance between TC, HDL, and FIB with cardiorespiratory fitness after adjusting for BMI is likely due to the biological relationship between cardiorespiratory fitness and BMI (r2 = 0.19).

CONCLUSIONS

We conclude that cardiorespiratory fitness is an important independent determinant of blood lipid and FIB levels in nonsmoking postmenopausal women, with or without HRT.

Effects of hormone replacement therapy on the endometrium and lipid parameters: a review of randomized clinical trials, 1985 to 1995

The association between unopposed estrogen replacement therapy and endometrial hyperplasia and endometrial cancer in nonhysterectomized postmenopausal women is well known, and studies have suggested that the addition of progestin to the regimen reduces the risk of hyperplasia and cancer. The effect of estrogen plus progestin hormone replacement therapy on the lipid profile has also been extensively studied. To determine the extent of the effects of hormone replacement therapy on the endometrium and lipid parameters and to provide an overview of these studies, we reviewed 10 years of English language publications.

Acute effects of a surgical menopause on serum concentrations of lipoprotein(a)

OBJECTIVE

The aim of this study was to investigate acute changes in serum concentrations of lipoprotein(a) and other atherogenic lipids and lipoproteins after a surgical menopause.

METHODS

A total of 100 premenopausal Chinese women who were booked for hysterectomy for benign gynecological disorders were recruited. They study group comprised 40 subjects undergoing hysterectomy as well as bilateral oophorectomy. The control group consisted of 60 subjects undergoing hysterectomy with conservation of the ovaries. Complete data were available from 30 of the 40 subjects in the study group and from 44 of the 60 controls. Serum concentrations of lipoprotein(a) and other atherogenic lipids and lipoproteins were measured before surgery and these measurements were repeated 3 days, 8 weeks and 6 months postoperatively. Those study patients who received hormone replacement therapy and control patients who became menopausal, according to biochemical criteria, during the study period were excluded from analysis.

RESULTS

Three days after surgery, there was a significant increase in the mean lipoprotein(a) concentration in the control group from 19.1 to 23.0 mg/dl (p < 0.01), but there was no significant change in the study group. There were no significant changes from baseline in the mean lipoprotein(a) concentration in either group 8 weeks or 6 months after surgery. There was a significant increase in the mean concentration of total cholesterol in the study group 8 weeks after surgery from 5.08 to 5.45 mmol/l (p < 0.01), in low density lipoprotein cholesterol from 3.22 to 3.49 mmol/l (p < 0.01), and in apolipoprotein B from 95.6 to 103.0 mg/dl (p < 0.05). However, the mean concentrations 6 months after surgery were not significantly different from baseline levels. The mean concentrations of high density lipoprotein cholesterol, apolipoprotein A-1 and triglycerides also did not differ significantly from baseline in the study group, either 8 weeks or 6 months after surgery.

CONCLUSIONS

These results suggest that any increase in concentrations of lipoprotein(a), and other atherogenic lipids and lipoproteins which occur after the menopause, develops relatively slowly. The changes in concentrations which occurred within 8 weeks of surgery were probably an acute-phase reaction after surgery rather than a response to a decreasing estradiol concentration.

Effect of naturally reduced ovarian function on plasma lipoprotein and 27-hydroxycholesterol levels in baboons (Papio sp.)

Female baboons over 15 years of age develop irregular menstrual cycles, an indication of declining ovarian function similar to that occurring in perimenopausal women. To determine the effect of declining ovarian function on plasma lipoprotein metabolism and plasma oxysterols, we measured plasma lipoprotein and 27-hydroxycholesterol levels in 86 female baboons from 15-28 years of age with regular (n = 51) and irregular (n = 35) menstrual cycles. We sampled blood and liver while they were consuming a basal diet and after consuming a high cholesterol and high fat diet for 7 weeks. On the basal diet, baboons with irregular cycles had higher VLDL + LDL/HDL cholesterol ratios (P = 0.034). After consuming the HCHF diet for 7 weeks, total plasma (P < 0.001) and VLDL + LDL (P < 0.001) cholesterol concentrations and VLDL + LDL/HDL sterol ratios (P < 0.001) increased in both cycle groups; whereas HDL cholesterol concentrations increased only in baboons with regular cycles (P = 0.009). As a result, HDL cholesterol concentrations (P = 0.006) were lower and VLDL + LDL/HDL cholesterol ratios (P = 0.002) were higher in baboons with irregular cycles on the HCHF diet. Plasma 27-hydroxycholesterol concentrations were higher in baboons with regular cycles than in those with irregular cycles on both basal (P = 0.018) and HCHF (P = 0.037) diets and were positively correlated (P < 0.001) with hepatic sterol 27-hydroxylase activities on both diets. Hepatic sterol 27-hydroxylase activities were negatively correlated with the VLDL + LDL/HDL cholesterol ratios on the HCHF diet (r = -0.342, P = 0.033). These results suggest that declining ovarian function changes the plasma lipoprotein pattern to one that is more atherogenic. Ovarian failure is also associated with decreased concentrations of plasma 27-hydroxycholesterol (the major oxysterol of plasma), and the decrease in plasma 27-hydroxycholesterol concentration was due to the decrease in hepatic sterol 27-hydroxylase activity. The effects of ovarian failure on plasma lipoprotein metabolism and plasma 27-hydroxycholesterol may be mediated by the decreased production of estrogen in perimenopausal baboons. Thus, the perimenopausal baboon is an excellent model for menopause and can be used for studies that cannot be conducted in women.

Relationship of endogenous sex hormones to lipids and blood pressure in mid-aged women

PURPOSE

The relationship between endogenous sex hormones and blood lipids was examined in a representative sample of 438 Australian-born women 45 to 56 years of age taking part in a longitudinal study of the menopausal transition. Data from 363 women who were taking neither exogenous hormones nor lipid-altering medications, were not diabetic, and who had provided blood samples were available for analysis.

METHODS

Multiple linear regression was used to examine the relationship between sex hormones and high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), triglycerides, and diastolic blood pressure (DBP), taking account of the effects of age, body mass index (BMI), smoking, alcohol intake, and exercise.

RESULTS

There was no significant relationship between estradiol and HDL, LDL, triglyceride, or DBP levels. Free androgen index was positively associated with LDL. However, BMI was an important predictor of all three lipid measures and DBP. HDL was positively associated with age and was highest among women with lowest BMI, high alcohol intake, and in nonsmokers. LDL increased with BMI, free androgen index, and age, but was lower amongst women who exercised more than two or three times per week. Triglyceride also increased with BMI, and was higher among smokers. DBP increased with BMI only.

CONCLUSIONS

The results do not support the view that endogenous sex hormones are strongly associated with cardiovascular risk factors around the time of menopause.

Is there a menopausal metabolic syndrome?

Estradiol-17 beta has beneficial effects on a range of metabolic risk factors for coronary heart disease and the decline in estrogen concentrations at the menopause would be expected to have adverse effects. Review of the literature on effects of the menopause and of estradiol-17 beta provides evidence for the following changes occurring at or after the menopause: increased total cholesterol and triglycerides; decreased high density lipoprotein (HDL) and HDL subfraction 2; increased low density lipoprotein, particularly in the small, dense subfraction; increased lipoprotein (a); increased insulin resistance; decreased insulin secretion; decreased insulin elimination; increased android fat distribution; impaired vascular function; increased factor VII and fibrinogen, and reduced sex-hormone binding globulin. Many of these changes will themselves have adverse effects on other metabolic risk factors. This complex of inter-correlated adverse changes in metabolic risk factors justifies identification of a distinct menopausal metabolic syndrome which originates in estrogen deficiency and which could contribute to the increased risk of coronary heart disease seen in postmenopausal women. Estrogen replacement can diminish the expression of this syndrome.

Estrogen and progestin compared with simvastatin for hypercholesterolemia in postmenopausal women

BACKGROUND

Postmenopausal estrogen therapy has favorable effects on serum lipoproteins in women with normal serum lipid levels, but the effect of combined estrogen and progestin therapy on lipoproteins in women with hypercholesterolemia has not been determined, nor has it been directly compared with the effect of conventional lipid-lowering therapy.

METHODS

In a randomized crossover trial, we studied 58 postmenopausal women with fasting serum total cholesterol levels greater than 250 mg per deciliter. Each woman received simvastatin (10 mg daily) for eight weeks and postmenopausal hormone therapy (up to 1.25 mg of conjugated equine estrogens daily, along with 5 mg of medroxyprogesterone acetate daily) for eight weeks, with an eight-week washout period between the two treatment phases.

RESULTS

At base line, the mean (+/-SD) cholesterol values were as follows: total cholesterol, 305+/-39 mg per deciliter; high-density lipoprotein (HDL) cholesterol, 62+/-19 mg per deciliter; and low-density lipoprotein (LDL) cholesterol, 217+/-39 mg per deciliter. For total cholesterol, the mean decrease with hormone therapy was 14 percent (95 percent confidence interval, 11 to 16 percent) and the mean decrease with simvastatin was 26 percent (95 percent confidence interval, 23 to 29 percent). For LDL cholesterol, the mean decrease was 24 percent (95 percent confidence interval, 20 to 28 percent) with hormone therapy and 36 percent (95 percent confidence interval, 32 to 40 percent) with simvastatin. The effect of simvastatin was significantly greater than that of hormone therapy (P<0.001). HDL cholesterol increased similarly with hormone therapy (mean increase, 7 percent; 95 percent confidence interval, 2 to 12 percent) and simvastatin (mean increase, 7 percent; 95 percent confidence interval, 4 to 10 percent). Triglyceride levels increased with hormone therapy (mean increase, 29 percent; 95 percent confidence interval, 15 to 42 percent) but decreased with simvastatin (mean decrease, 14 percent; 95 percent confidence interval, 8 to 20 percent). Lp(a) lipoprotein decreased with hormone therapy (mean decrease, 27 percent; 95 percent confidence interval, 20 to 34 percent), but not with simvastatin.

CONCLUSIONS

In postmenopausal women with hypercholesterolemia, therapy with estrogen plus progestin has beneficial effects on lipoprotein levels. Hormone therapy may be an effective alternative to treatment with simvastatin, especially in women with normal triglyceride levels.

Longitudinal trends in total serum cholesterol levels in a Japanese cohort, 1958-1986

The 28-year follow-up of a Japanese cohort, having collected vast amounts of data collected on total serum cholesterol (TC), provided an exceptional opportunity to examine TC temporal trends. The longitudinal statistical method of growth-curve analysis was used to elucidate the age-related changes in TC levels and to characterize these trends in relation to sex, birth cohort, time period, place of residence, and body mass index (BMI). Japanese TC levels at initial examination were remarkably lower than those in western countries. During the study period from 1958 to 1986, TC levels increased dramatically with age in both sexes. The slope of the cholesterol growth curve was steeper for women than for men, with the difference growing larger after age 40 years. Drastic changes in Japanese behavior and lifestyle, especially westernization of the diet, are thought to have affected the TC values as time-period effects. As a result of this temporal change, which affected different cohorts at different ages, TC values were higher in members of the younger cohort. The increase of the TC values as time-period effects were larger in earlier period than in later period. These time-period effects appeared to be almost similar in men and women. The TC growth curves also varied by city of residence. Subjects in urban areas had higher TC values than subjects in rural areas. Changes associated with BMI from 1958 to 1986 were only partially responsible for the increased steepness of the TC growth curve.

Estrogen deprivation, rather than age, is responsible for the poor lipid profile and carbohydrate metabolism in women

The protective effect of estrogen against cardiovascular diseases (CVD) in women disappears after menopause. However, it is not clear whether the change in risk factors after menopause is related to aging or estrogen deprivation.

OBJECTIVE

To assess the risks for CVD and the contribution of aging in estrogen-deprived women.

METHODS

Forty-one patients with premature ovarian failure (POF) (group 1) and 30 patients with natural menopause (group 2) were investigated with respect to well-known risk factors for CVD. Fifteen young women at reproductive age (group 3) were taken as controls. The median ages (ranges) of the groups were 31 (19-40), 52 (46-67) and 26 (24-29) years, respectively. Family and personal history for CVD, smoking, oral contraceptive usage, physical examination, blood pressure measurement, body mass index (BMI), blood level of fasting insulin, diabetes mellitus, and the levels of lipoprotein proteins were the examined parameters regarding the risks for CVD.

RESULTS

The levels of triglycerides and very low density lipoprotein (VLDL) cholesterol were not different in the 3 groups. The levels of fasting insulin (11.3 +/- 6.6 vs. 10.2 +/- 5.8 IU/ml), the ratio of fasting insulin to fasting blood glucose (12.2 +/- 6.3% vs. 10.5 +/- 5.4%), high density lipoprotein (HDL) cholesterol (51.9 +/- 12.9 vs. 51.6 +/- 9.7 mg/d), low density lipoprotein (LDL) cholesterol (113 +/- 47 vs. 127 +/- 37 mg/dl) and the ratio of HDL to total cholesterol (27.2 +/- 9.8% vs. 24.1 +/- 6.9%) were not different in women with POF and natural menopause. These parameters were all better in controls with respect to risk for CVD (respectively, 6.5 +/- 2.0 IU/ml, 7.4 +/- 2.2%, 37.9 +/- 5.3 mg/dl, 80 +/- 40 mg/dl, P < 0.05).

CONCLUSION

Risk factors for CVD are related to estrogen deprivation. Aging does not have an important impact on CVD within the age range of this study group.

The menopausal transition

The menopausal transition is that period beginning with the first indications of the approach of menopause and ending with the final menses. Its morphological basis is a rapidly declining number of primordial follicles within the ovary; a decline which appears to result from an increased rate of follicular atresia. The most characteristic hormonal change in the menopausal transition is a progressive, though often fluctuating, rise in the level of serum FSH. Oestradiol and inhibin levels fluctuate markedly when observed in individual subjects but remain relatively preserved during the follicular phase of the cycle, until late in the menopausal transition. The frequency of anovulatory cycles increases as the final menstrual period approaches. The rate of symptom reporting varies among different populations of women, with maximum symptom frequency being seen during the menopausal transition. There are some indications that cardiovascular and osteoporosis risk factors may change adversely during the menopausal transition and medical practitioners should be ready to offer hormonal supplementation to women at increased risk of cardiovascular disease and osteoporotic fracture.

Metabolic effects of the menopause and oestrogen replacement

There is little doubt that the metabolic disturbances seen following the loss of ovarian function are most important in the development of cardiovascular disease in women. The loss of hormones at the menopause appears to reduce both insulin secretion and elimination, but increasing insulin resistance thereafter brings about an increase in circulating insulin concentrations. Changes in lipids and lipoproteins are in an adverse direction, as are changes in body fat distribution, and changes in haemostatic factors would tend to favour coagulation rather than fibrinolysis. HRT with oestrogen appears to improve most of the metabolic abnormalities related to the menopause, but this is in part dependent on the type of oestrogen used and the route of administration. The addition of progestogen may influence the metabolic changes induced by oestrogens, and this will vary according to the type of the progestogen. Overall, the metabolic effects of any of the current HRT regimens would seem likely to be beneficial for CHD. Nevertheless, future HRT regimens should ideally be tailored to produce the most favourable changes in CHD metabolic risk factors, particularly in the case of the regimens which attempt to avoid cyclical bleeding.

Effects of menopause on trends of serum cholesterol, blood pressure, and body mass index

BACKGROUND

To elucidate the impact of menopause on coronary risk factors, we determined the trends of serum cholesterol (mg/dL), blood pressure (BP, mm Hg), and body mass index (BMI, kg/m2) and investigated whether menopause affects these trends in women in Nagasaki, Japan.

METHODS AND RESULTS

Trends of cholesterol, systolic BP (SBP), and BMI from 9 years before menopause through 9 years after menopause in 579 women with natural menopause (ranging in age from 40.2+/-3.1 to 57.9+/-3.1 years; age at menopause, 49.4+/-3.0 years) and 134 women with surgical menopause (hysterectomy with or without bilateral oophorectomy; ranging in age from 34.9+/-4.5 to 51.7+/-5.1 years; age at menopause, 42.9+/-5.0 years) and those in 579 and 134 age- and time-matched male subjects (ranging in age from 40.1+/-3.1 to 57.8+/-3.2 years and from 35.2+/-4.5 to 51.6+/-5.0 years, respectively) in Nagasaki were determined by rearrangement of the data from 1958 to 1989 with time of menopause as the datum line. Although cholesterol tended to increase with age in both sexes, it increased significantly in women from 3 years before natural menopause to 1 year after natural menopause and from 1 year before surgical menopause to 1 year after surgical menopause. SBP and BMI did not exhibit a significant increase in relation to natural or surgical menopause. In male subjects, no significant increase of cholesterol, SBP, or BMI was observed at the age corresponding to natural or surgical menopause.

CONCLUSIONS

Natural menopause and surgical menopause exert an effect only on cholesterol, and an increase in cholesterol precedes natural menopause by 3 years and occurs at the time of surgical menopause.

The effect of surgical castration on lipid metabolism in premenopausal and postmenopausal women

OBJECTIVE

To investigate the effect of endogenous estrogen on lipid and lipoprotein metabolism in premenopausal and postmenopausal women.

DESIGN

Prospective randomized study.

SETTING

Department of Obstetrics-Gynecology, Beilinson Medical Center and Tel-Aviv University Medical School, Israel.

SUBJECTS

Twenty-seven women, 15 premenopausal and 12 postmenopausal, undergoing surgical castration (total abdominal hysterectomy and bilateral salpingo-oophorectomy).

METHOD

Blood samples were drawn before the surgical intervention and after a 6-month interval.

MAIN OUTCOME MEASURES

Assays were performed for estradiol, luteinising hormone and follicle-stimulating hormone, and triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol and total cholesterol/HDL as well as HDL/LDL ratio.

RESULTS

No significant differences were found in both groups, before castration and after 6 months. A modest, but statistically significant, rise in triglycerides was observed in the premenopausal group.

CONCLUSIONS

The serum lipid and lipoprotein profile encountered in premenopausal and postmenopausal women were unchanged 6 months after surgical castration. The clinical significance indicates that the effect of endogenous estrogen on lipid metabolism is doubtful and should be further investigated.

The menopause and hormone replacement therapy: lipids, lipoproteins, coagulation and fibrinolytic factors

OBJECTIVES

To review the recent literature concerning the effects of the menopause and hormone replacement therapy (HRT) on the plasma lipoprotein and hemostatic system, as well as on the interaction between these two coronary heart disease (CHD) risk factor systems. METHODS. Collection of information from relevant scientific journals, and by the use of Medline and Current Contents.

RESULTS

The mainly beneficial effects of unopposed oral estrogen replacement on the plasma lipoprotein pattern are preserved to different degrees after addition of progestin to the regimen. Nortestostorone-derived progestins tend to lower HDL cholesterol levels more than progesterone derivatives. The slight triglyceride-elevating effect on conjugated equine estrogens was in a large study not significantly counteracted by progesterone derivatives but can, according to other studies, be reversed by nortestosterone-derived progestins. A limited number of studies on transdermal administration of estradiol has suggested that the effects on plasma lipoproteins are smaller than during oral administration. There is no convincing evidence that currently used HRT regimens would significantly increase the risk of thrombosis. Nevertheless, the finding in some studies that plasma triglyceride elevations could in theory be associated with impaired fibrinolysis and enhanced coagulation merit further attention as some HRT regimens tend to increase plasma triglyceride levels. From a theoretical point of view, transdermal estrogen delivery would be preferable in women at risk for thrombosis, as they have less pronounced effects on liver functions, including production of hemostatic factors and very-low-density lipoprotein triglycerides.

CONCLUSIONS

While the numerous existing HRT regimens provide many alternative and useful possibilities, further studies are needed concerning (a) novel progestins with minimal HDL cholesterol lowering effects, (b) transdermal and other non-oral routes for HRT, (c) possible antioxidative properties of estrogen and (d) metabolic links between the lipoprotein and hemostatic risk factor systems.

Effect of postmenopausal estrogen replacement therapy on lipoproteins

OBJECTIVES

To investigate the association between menopause and lipoproteins and the effect of hormone replacement therapy (HRT).

METHODS

Total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides were estimated in 50 postmenopausal women and 25 ovulating women who served as controls. The lipoprotein estimations were repeated after 1 year of therapy with natural estrogen-norgestrel combination.

RESULTS

More postmenopausal women than younger women had lipoprotein values in the high-risk status (P <0.001). There were no significant changes in lipoprotein levels (P >0.05) after HRT. Women with a body mass index below 26 kg/m2 had a significant reduction in their lipoprotein risk status (P <0.01).

CONCLUSION

There was no demonstrably clear effect of the estrogen-progestin combination on lipoprotein levels, probably because of other compounding variables such as obesity, lack of exercise and the type of progestin used.

Perimenopausal changes in serum lipids and lipoproteins: a 7-year longitudinal study

Although cross-sectional studies suggest considerable influence of menopause on serum lipids and lipoproteins in women, it is not exactly clear. During our 7-year longitudinal study, serum concentrations of total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and low-density lipoprotein (LDL) cholesterol were measured in 16 healthy perimenopausal women (aged 47-56 years at menopause) who had undergone annual examinations 4 years before and 3 years after menopause under a health examinations system in Osaka. Longitudinal design enabled us to study the natural course of serum lipids and lipoproteins. The results show that from 4 years before to 1 year after menopause, the serum concentration of total cholesterol and LDL cholesterol increased on average by 25 mg/dl (14%) and 20 mg/dl (19%), respectively. Serum concentrations of triglycerides and of HDL cholesterol remained virtually unchanged during the perimenopausal and postmenopausal periods. It was concluded that serum lipids and lipoproteins are thus significantly altered as a consequence of menopause, resulting in a more atherogenic profile in the postmenopausal period.

Body composition and serum lipids in female runners: influence of exercise level and menstrual bleeding pattern

The impact of running and menstrual disturbances on regional and total body fat distribution and serum lipids was investigated in 205 women. Body composition was measured by dual-energy X-ray absorptiometry. The total fat mass in the elite runners was approximately half of the normally active's (7.3 [0.48] kg vs. 14.3 [0.49] kg, P < 0.001) (mean [SEM]). The difference was most pronounced in the abdomen (fat percentage 9.7 [0.85]% vs. 22.0 [0.88]%, P < 0.001). The elite runners tended to have a more favourable lipid profile than the normally active (NS). A significant relation was found between lipoproteins and body fatness. In comparison with the regularly menstruating runners (n = 93), the 13 runners with amenorrhea tended to have less body fat and slightly less favourable lipid profiles (NS). In conclusion, regular exercise was associated with a low abdominal fat percentage, which may affect cardiovascular risk beneficially. Running-associated menstrual dysfunctions were not significantly related to a specific body composition or serum lipid profile.

Serum lipids and lipoproteins in postmenopausal women receiving transdermal oestrogen in combination with a levonorgestrel-releasing intrauterine device

OBJECTIVES

To compare the effects of a non-oral combination of a transdermal oestradiol patch (50 micrograms daily) and an intrauterine device (IUD) releasing 20 micrograms of levonorgestrel daily on the serum pattern of lipids and lipoproteins with an established oral regimen of a daily dose of 2 mg of estradiol and 1 mg of noretisterone acetate.

METHODS

An open, randomized study comprised of 40 healthy, early postmenopausal women.

RESULTS

During 1 year the concentration of total cholesterol decreased 5.0% in the LNg-IUD group and 10.6% in the oral therapy group; HDL cholesterol decreased 10.9% and 12.8%, respectively, and HDL2 cholesterol decreased 18.1% and 26.9%, respectively. LDL cholesterol values did not change in the LNg-IUD group, whereas a 10.3% decrease was observed in the oral therapy group. Triglyceride values did not change in either group. There were no significant differences in the serum lipoprotein changes between the groups during the treatment.

CONCLUSIONS

The use of a non-oral regimen of hormone replacement therapy has been advocated to minimize the effect of steroids on the liver. Its effects on the serum pattern of lipids and lipoproteins, however, did not differ significantly from those induced by a continuous oral treatment regimen.

Thoughts on gender-related research: Models, myths, and medicine

Gender-related research directed to hypertension and coronary artery disease (CAD) is discussed in terms of the one-sex and two-sex models. Gender "blind" research on the two conditions has resulted in questionable treatment regimes for women. In addition, the biomedical myth of CAD as a male disease has also perpetuated less-than-optimal treatment. Finally, the role of amount and distribution of body fat in the development of hypertension and CAD should be considered within an evolutionary framework. Body fatness in women has been of evolutionary survival value and current standards for ideal weight and risk for disease have to take this into account. © 1995 Wiley-Liss, Inc.

Ethnic differences in lipid and lipoprotein metabolism in pregnant women of African and Caucasian origin

AIMS

To investigate differences in serum lipid, lipoprotein and apolipoprotein concentrations in pregnant women of different ethnic origin.

METHODS

Serum lipid, lipoprotein and apolipoprotein concentrations were measured in 232 women (114 Caucasians, 118 Africans/Afro-Caribbeans), who presented consecutively for screening for gestational diabetes in the third trimester of pregnancy.

RESULTS

African/Afro-Caribbean pregnant women had lower serum concentrations of total cholesterol, low density lipoprotein cholesterol, triglycerides, and apolipoprotein B and higher high density lipoprotein cholesterol and Lp(a) lipoprotein concentrations compared with Caucasian women. Apolipoprotein A1 concentrations were similar in the two groups. The differences were not attributable to differences in weight, age, parity, or postload plasma glucose levels.

CONCLUSION

Ethnic origin is an important determinant of serum lipid, lipoprotein and apolipoprotein concentrations during pregnancy.

Natural menopause and cardiovascular disease risk factors. The Poland and US Collaborative Study on Cardiovascular Disease Epidemiology

Changes in risk factor levels associated with menopause have been reported in many studies in the United States and western Europe, where estrogen replacement therapy and surgical menopause are common. We studied risk factor associations in Polish women, for whom estrogen replacement therapy and surgical menopause are uncommon. The 357 postmenopausal women had higher total cholesterol levels (0.43 mmol/L) and low-density-lipoprotein cholesterol levels (0.36 mmol/L than did the 372 premenopausal women of similar ages. Triglycerides, high-density-lipoprotein cholesterol, body mass index, and blood pressure did not differ by menopausal status. We conclude that natural menopause is associated with higher levels of total and low-density-lipoprotein cholesterol levels. Natural menopause is not associated with large changes in other risk factors in this sample.

Serum ferritin, sex hormones, and cardiovascular risk factors in healthy women

The protective effect of endogenous sex hormones is commonly believed to explain the gender gap in the risk of coronary heart disease and the diminished protection in women when menopause occurs. Recent reports indicate that iron overload, due to cessation of menstrual bleeding, may be an important factor. We therefore investigated iron stores by serum ferritin measurements in healthy premenopausal (n = 113) and postmenopausal (n = 46) women. Ferritin levels were higher in postmenopausal than in premenopausal women, both in blood donors (43.4 versus 23.1 micrograms/L, P < .001) and in nondonors (71.7 versus 32.8 micrograms/L, P < .001). Serum ferritin was positively correlated with age (r = .36, P < .001). After age adjustment, serum ferritin was positively correlated with hemoglobin, hematocrit, serum total cholesterol, and low-density lipoprotein (LDL) cholesterol. Total cholesterol was correlated with age (r = .66, P < .001), as were LDL cholesterol (r = .60, P < .01) and high-density lipoprotein cholesterol (r = .32, P < .01). Neither ferritin nor serum lipids were directly associated with female sex hormone levels. The mutual relation between ferritin, hemoglobin, and hematocrit probably only indicates their usefulness as measures of body iron. The parallel rise in serum ferritin, total cholesterol, and LDL cholesterol might contribute to the increased risk of coronary heart disease among postmenopausal women.

Effects of 2 years of hormone replacement upon bone mass, serum lipids and lipoproteins

The objective of this study was to measure the effects on postmenopausal women of 2 years of either a low dose or a moderate dose regimen of hormone replacement upon bone mass and serum cardiovascular risk factors. After 6 months of calcium supplementation, 75 women chose to add hormone replacement or to remain on calcium. Those choosing hormones were randomised to either 0.3 mg/day equine estrogen and 2.5 mg/day medroxyprogesterone or 0.625 mg/day equine estrogen, days 1-25, and 5 mg/day medroxyprogesterone, days 16-25. On calcium only, lumbar spine bone mineral content and radius bone mass fell. Serum concentrations of cholesterol and triglycerides increased while HDL concentration fell. The low dose continuous regime reduced whole body bone turnover and prevented the age related reductions in bone mass and serum cardiovascular risk profile. The moderate dose regimen reduced whole body bone turnover and increased lumbar spine bone mass. Total serum cholesterol was unchanged while HDL levels increased, LDL levels fell and triglyceride concentration increased.

Impact of the menopause on the epidemiology and risk factors of coronary artery heart disease in women

Cardiovascular disease is the leading cause of morbidity and mortality in women, and coronary artery heart disease (CHD) is the largest single component of fatal cardiovascular disease. Gender-related differences are observed in the symptomatology, natural course and outcome, and in the management of the acute coronary event. More women, compared to men, have angina as their first manifestation of CHD, and they are less likely to have serious stenosis. Women undergo less invasive diagnostic procedures, but have an overall prognosis that is worse than that of men. Rates of CHD in women increase after the fifth-sixth decades of life, suggesting that young women have a protective factor that is lost after the fifth decade. Because most women become menopausal during this age range, it is speculated that the protective factor may the female hormone, estrogen. This conclusion is supported by results of epidemiological studies indicating an increased risk of CHD in women with early-onset menopause and a reduced risk in postmenopausal women treated with estrogen replacement therapy. The impact of the menopausal transition on other CHD risk factors is still not fully understood. Reduced estrogen levels resulting from the menopausal transition have been implicated in adverse effects on obesity and fat distribution, plasma lipid profile, and rheological properties of plasma and platelet function. Postmenopausal estrogen deficiency may also aggravate preexisting diabetes mellitus and hypertension, and have an overall negative effect on the reaction to stress. These data suggest that estrogen deficiency can directly and indirectly promote CHD in women. More research is needed to clarify and differentiate menopause-related from aging-related effects on the risk of CHD women.

The effect of progestins on behavioral stress responses in postmenopausal women

OBJECTIVE

We assessed the effects of progestin when added to estrogen on the adaptive patterns to provoked stress in postmenopausal women.

METHODS

Fourteen postmenopausal women were randomized to receive either a transdermal estrogen patch (TE2) (n = 7) for 6 weeks or TE2 with added medroxyprogesterone acetate (10 mg) (TE2/MPA) (n = 7) for the last 10 days of the 6-week regimen. Behavioral stress tests were administered to each group, with measurements of biophysical and neuroendocrine responses. In a crossover fashion, after each group received the first treatment and testing, treatment was continued for another 6 weeks with the alternate regimen, at which time another stress test was administered. Responses to stress in the two treatment groups were compared to each other and to established placebo responses.

RESULTS

Biophysical responses in the TE2 group were significantly blunted compared to both TE2/MPA and placebo responses (P < .05). Without MPA treatment, there were significantly blunted speech (P < .05) and cold pressor (P < .01) blood pressure responses. With added progestin, there was a greater systolic blood pressure response (P < .01) compared with estrogen alone. Both groups (TE2 and TE2/MPA) had blunted and nonsignificant responses of ACTH and cortisol upon testing, whereas the placebo group showed a significant response (P < .01). Plasma norepinephrine responses, however, were significantly blunted after TE2, compared with the increased responses observed with both TE2/MPA and placebo (P < .01).

CONCLUSION

Although estrogen significantly reduces behaviorally induced stress reactivity in postmenopausal women, certain doses of progestin administration may blunt this effect.

Influence of spontaneous and surgical menopause on atherogenic metabolic risk

We evaluated serum total-, LDL-, HDL-, cholesterol and triglycerides in 858 women. Sixty-seven were in premenopause, 307 in perimenopause, 326 in spontaneous menopause, and 158 women underwent hysterectomy. Of these, 101 had bilateral ovariectomy, 24 with unilateral ovariectomy and 33 with retention of both ovaries. After correcting for chronological age and body mass index by variance analysis, it was found that total-, LDL- and HDL-cholesterol significantly increased during menopause without changes in the total cholesterol/HDL-cholesterol, LDL-cholesterol/HDL-cholesterol and triglycerides/HDL-cholesterol ratio. The changes gradually occurred during the months preceding spontaneous cessation of menses. Atherogenic metabolic risk (as relative risk of high total and LDL-cholesterol, estimated by logistic regression analysis) significantly increased in all groups of women in reference to premenopause. The risk observed in surgical menopause with bilateral ovariectomy was higher than in spontaneous menopause, and conservation of ovaries in hysterectomized women seems to protect only partially against such an increase.

Long-term effects of transdermal and oral estrogens on serum lipids and lipoproteins in postmenopausal women

The transdermal and oral administration of estrogens for one year were compared with respect to the effects on lipid metabolism. Eighty-one postmenopausal women (1.5-3 years after menopause) were randomly divided into three groups. The first two groups received sequential estrogen treatment with either transdermal estradiol (Estraderm TTS, Ciba Geigy; 50 micrograms/day; 24 women) or 0.625 mg/day conjugated estrogens (Premarin, Wyeth; 20 subjects), respectively. In both groups medroxyprogesterone (10 mg/day per os) was added for 12 days of each cycle. Thirty-five subjects served as control group without therapy. No significant changes in the lipid profile was observed in control subjects after 1 year of follow-up. Serum triglycerides decreased significantly (-10.9 +/- 26% S.D.; P < 0.05) in transdermal treated women, whereas it slightly rose in oral estrogen group. Comparable significant decreases in total and low density lipoprotein (LDL) cholesterol (mean range -6.5/-18.0%) were observed in women on estrogen replacement therapy. High density lipoprotein (HDL) cholesterol significantly diminished in transdermal estradiol group, but it rose slightly in the oral estrogen group. Thus the fraction of HDL cholesterol over LDL cholesterol did not change in the transdermal group whereas it significantly rose in subjects treated with oral estrogens. It remains to be established to what extent these differences on lipid metabolism are relevant for the prevention of cardiovascular diseases.

Blood flow variations in internal carotid and middle cerebral arteries induced by postmenopausal hormone replacement therapy

OBJECTIVE

Our purpose was to clarify the mechanisms by which postmenopausal estrogen replacement therapy exerts its protective effect on cardiovascular risk.

STUDY DESIGN

By means of a bidirectional Doppler ultrasonographic system we measured pulsatility index variations the internal carotid artery and middle cerebral artery in 25 early postmenopausal women during a 6-month period of hormone replacement therapy. Transdermal estradiol (50 micrograms/day) was continuously administered. A 12-day course of medroxyprogesterone acetate (10 mg/day) was added every second month.

RESULTS

The pulsatility index showed a significant (p = 0.0001) reduction in both arteries after 6 weeks. At 22 weeks a 25% reduction was measured. No variation of the estrogen-induced pulsatility index reduction was observed at the end of every cyclic progestogen supplementation.

CONCLUSIONS

In early postmenopausal women hormone replacement therapy causes a rapid reduction of pulsatility index in brain arteries. Cyclical progestational supplementation does not modify this positive effect on reactivity of the blood vessels.

Current concepts in estrogen replacement therapy in the menopause

OBJECTIVE

To provide a review of the risks and benefits of hormonal replacement therapy in the menopause, including new therapeutic regimens and modes of delivery.

DESIGN

A review of the literature to identify published studies was accomplished using a computerized bibliographical search (Medline).

RESULTS

Replacement therapy is effective in treating symptoms of estrogen deficiency and in lowering the risk of osteoporosis and cardiovascular disease. The daily administration of an estrogen and progestin eliminates the withdrawal bleed and increases patient compliance. This continuous form of therapy also consistently suppresses the endometrium, decreasing the risk of hyperplasia. More studies investigating the effect of continuous therapy on the lipid profile and cardiovascular disease are needed.

CONCLUSIONS

New therapeutic regimens and modes of delivery decrease risk and increase patient acceptance of hormonal replacement therapy.

A novel oestradiol--desogestrel preparation for hormone replacement therapy: effects on hormones, lipids, bone, climacteric symptoms and endometrium

Desogestrel is a strong progestogen with low androgenicity which has so far been used only in oral contraceptives. We studied the feasibility of administering desogestrel in combination with oestradiol as hormone replacement therapy (HRT). Thirty women received a sequential combination containing 1.5 mg micronised oestradiol (24 days) and 0.15 mg desogestrel (last 12 days of cycle) for 6 months. At that stage 6 of the women dropped out; the remaining 24 were studied for a total of 12 months. The treatment alleviated vasomotor symptoms effectively in all the women and induced regular withdrawal bleeding in 86% of them. Secretory changes were observed in the endometria of 16 of the 20 women with adequate endometrial samples assessed after 12 months of treatment. No signs of hyperplasia or atypia were found. Six months of treatment resulted in a decrease in the mean serum follicle-stimulating-hormone concentration from 66.2 (+/- 4.3, S.E.M.) to 23.3 (+/- 3.1) IU/l and a rise in the oestradiol and sex-hormone-binding globulin concentrations from 87.9 (+/- 13.7) to 233.1 (+/- 20.4) pmol/l and from 52.1 (+/- 4.6) to 70.2 (+/- 5.6) nmol/l, respectively. Testosterone levels decreased. There were significant reductions in serum total and low density lipoprotein (LDL) cholesterol and triglycerides. After 12 months of treatment high-density lipoprotein (HDL) cholesterol values did not differ significantly from the pretreatment levels. The HDL/LDL and HDL/total cholesterol ratios increased. The treatment reduced bone turnover as indicated by decreases in bone alkaline phosphatase and osteocalcin serum levels and by lowered urinary calcium/creatinine and hydroxyproline/creatinine ratios. An increase of about 2% in forearm bone mineral density was also observed. This new oestradiol-desogestrel preparation therefore appears to be a promising alternative form of HRT. It alleviates climacteric symptoms effectively, exhibits favourable effects on serum lipids and lipoproteins and prevents bone loss.

Oestrogens and atherosclerotic vascular disease--lipid factors

Cardiovascular disease remains the major cause of death for postmenopausal women in Western societies. The majority of epidemiological studies indicate that postmenopausal oestrogen replacement therapy is associated with a 50% reduction in the risk of cardiovascular disease, with much of the reduction being mediated by changes in the plasma concentration of cholesterol within high and low density lipoproteins. In addition to favourably influencing the plasma concentration of lipoproteins, oestrogens also influence the complex metabolism of lipoproteins in the arterial wall, helping to impede the formation of the atherosclerotic plaque. Whilst oestrogens alter endothelial function, vascular reactivity and fibrinolysis, these changes are also seen with reduction of LDL cholesterol and may partly reflect the altered concentration of plasma lipoproteins induced by oestrogens. Oral oestrogens have substantially greater favourable effects on LDL and HDL cholesterol than their transdermal counterparts but also result in greater hypertriglyceridaemia. Most progestogens antagonize the beneficial effects of oestrogens on lipoproteins in a dose-dependent manner; however, cyclical use of low doses of progestogens with an oral oestrogen generally retains a net beneficial effect. Lipoprotein levels fluctuate during cyclical therapy, the most adverse changes being noted at the end of the progestogen phase. Lipoprotein concentrations are constant during continuous combined regimens which have the potential for more prolonged exposure to an adverse progestational effect. Despite adverse effects on the lipoprotein profile, animal studies suggest that progestogens do not substantially reverse the beneficial effects of oestrogens on the development of atherosclerosis. Finally, oestrogen therapy may be useful in the management of postmenopausal women with hyperlipidaemia, and also in the secondary prevention of clinical sequelae in women with established atherosclerosis.

Plasma lipid and lipoprotein effects of transdermal administration of estradiol and estradiol/norethisterone acetate

To evaluate the effect of transdermal sequential treatment with estradiol and estradiol/norethisterone acetate on lipoprotein metabolism, 25 postmenopausal women received treatment for 12 cycles of 4 weeks each (2 weeks estradiol 50 micrograms/day and 2 weeks a combined patch delivering norethisterone acetate 0.25 mg/day and estradiol 50 micrograms/day). Blood samples for lipoprotein analyses were drawn before treatment and in estrogen and combined phases in cycles 3 and 12. Plasma total cholesterol, low (LDL) and high (HDL) density lipoprotein were all significantly reduced in both estrogen and combined phases. Eighteen of the women continued the treatment for 36 cycles. In this group the HDL-cholesterol had returned to baseline values in combined phase in cycle 24. Plasma cholesterol and LDL-cholesterol values remained significantly reduced throughout the whole study compared to the pre-trial values. The present study by transdermal sequential hormonal treatment results in a lipid and lipoprotein pattern with reduced total cholesterol and LDL cholesterol in postmenopausal women.

Racial differences in lipid and lipoprotein levels in diabetes

Racial differences in plasma lipid and lipoprotein levels were investigated in 145 patients with non-insulin-dependent diabetes mellitus (NIDDM). Black men had higher high-density lipoprotein (HDL) cholesterol levels, lower triglyceride levels, and an improved atherogenic index compared with white men. Premenopausal black women were also found to have higher HDL cholesterol levels, lower triglyceride levels, and a lower atherogenic index than their white counterparts. Adjustment for age, waist to hip ratio (WHR), hemoglobin A1c (HbA1c), and physical activity did not eliminate the significant differences found. There were no racial differences found regarding total and low-density lipoprotein (LDL) cholesterol. Metabolic control as measured by HbA1c was significantly correlated with the triglyceride level in black women. These data confirm that racial differences exist in plasma lipid levels among patients with NIDDM.

The role of progestins in hormone replacement therapy

Long-term estrogen replacement therapy prevents osteoporosis and reduces the risk of cardiovascular disease in postmenopausal women. Progestins are used to prevent endometrial hyperplasia and carcinoma but should not be prescribed for women who have had hysterectomies. Doses that decrease mitotic activity are sufficient. Recent data suggest that a continuous combined regimen of estrogen and progestin may increase bone mass in women who have established osteoporosis. Some progestins may oppose the beneficial effects of estrogen on the cardiovascular system in some women. Critical cardiovascular effects of progestins include a reduction in the serum level of high-density lipoprotein cholesterol and a direct effect on arterial tone, which may be mediated by an attenuation of prostacyclin production and other factors. Therefore it is prudent to prescribe the lowest effective dose of a progestin that demonstrates the least metabolic impact. The dose and type of progestin should be balanced with the estrogen component so that the estrogen-dominant metabolic effects prevail. With this approach the difference in mortality rates between women who use unopposed estrogen and women who use estrogen-progestin therapy will be minimized and will make the appropriate sequential addition of progestin an option in postmenopausal hormone replacement therapy.

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.

Changes in lipids and lipoproteins with long-term estrogen deficiency and hormone replacement therapy

Cross-sectional data of the long-term effects of estrogens, androgens, and progestogens on lipids and lipoproteins were obtained in 556 postmenopausal women aged 24 to 85 years with follow-up for 1 to 44 years. Baseline values were obtained in 155 women from less than 1 year up to 30 years after menopause. Total cholesterol and low-density lipoprotein cholesterol tended to rise during the early postmenopausal years while high-density lipoprotein cholesterol did not change. Triglycerides were related to weight and were significantly different only between untreated women of normal weight (128.3 +/- 7.80 mg/dl) and hormone users weighing greater than 200 pounds (252.9 +/- 9.44 mg/dl), p less than or equal to 0.001. Although mean high-density lipoprotein cholesterol was lower with both C-21 progestogens (64.5 +/- 4.16 mg/dl) and C-19 progestogens (61.9 +/- 3.84 mg/dl), there were no statistically significant differences on comparison with levels in the unopposed estrogen users (67.0 +/- 3.94 mg/dl). Smoking significantly depressed high-density lipoprotein cholesterol in both hormone users (p less than or equal to 0.001) and untreated women (p less than or equal to 0.001). Added progestogens do not adversely affect lipids and lipoproteins over the long term when adequate dosages of estrogens are used.