Temporal changes in clinic and ambulatory blood pressure during cyclic post-menopausal hormone replacement therapy

The effect of 17β-estradiol plus norethisterone acetate on blood pressure and inflammation markers: A meta-analysis of randomized controlled trials

OBJECTIVE

Several randomized controlled trials (RCTs) have explored the impact of 17β-estradiol plus norethisterone acetate administration on blood pressure and inflammation markers, however, their findings have often been contradictory. Thus, we conducted a systematic review and meta-analysis of RCTs to assess the effects of this drug combination on systolic blood pressure (SBP), diastolic blood pressure (DBP) and C-reactive protein (CRP) concentrations.

METHODS

The Cochrane Library, PubMed/Medline, Scopus, and Google Scholar were searched to identify relevant published RCTs. The pooled mean change and standard deviation (SD) of the outcomes were calculated using the STATA software (version 14) for Statistical Computing.

RESULTS

A total of 18 publications were included in the current meta-analysis. In total, there were 12 RCT arms on SBP, 12 RCT arms on DBP, and 6 RCT arms on CRP levels. The administration of 17β-estradiol plus norethisterone acetate intake increased SBP (WMD: 3.48 mmHg, 95% CI: 0.73, 6.23, P = 0.013), particularly in subjects aged ≥ 60 years (WMD: 5.89 mmHg, 95% CI: 1.71, 10.07, P = 0.006) or with a body mass index (BMI) < 30 kg/m² (WMD: 6.55 mmHg, 95% CI: 2.64, 10.46, P = 0.012), as well as in the RCTs which lasted ≥ 6 months (WMD: 6.47 mmHg, 95% CI: 3.03, 9.90, P < 0.001),when 17β-estradiol dosages were ≥ 2 mg/day (WMD: 4.12 mmHg, 95% CI: 1.03, 7.22, P = 0.009; I² = 99%, P < 0.001) and in RCTs conducted on healthy postmenopausal women (WMD: 4.22 mmHg, 95% CI: 0.43, 8.01, P = 0.02; I² = 94%, P < 0.001). DBP decreased following this drug combination in the RCTs which lasted < 6 months (WMD: -1.42 mmHg, 95% CI: -2.27, -0.57, P = 0.001). CRP concentrations increased following the use of this drug combination (WMD: 1.01 mg/L, 95% CI: 0.62, 1.41, P < 0.001), especially in participants aged < 60 years (WMD: 1.22 mg/L, 95% CI: 0.77, 1.68, P < 0.001) or with a BMI < 30 kg/m² (WMD: 0.97 mg/L, 95% CI: 0.67, 1.27, P < 0.001), as well as in RCTs with a duration of ≥ 6 months (WMD: 1.15 mg/L, 95% CI: 0.57, 1.73, P < 0.001), when 17β-estradiol dosages were ≥ 2 mg/day (WMD: 0.97 mg/L, 95% CI: 0.67, 1.27, P < 0.001; I² = 55%, P = 0.107) and in RCTs conducted on healthy postmenopausal women (WMD: 1.22 mg/L, 95% CI: 0.77, 1.68, P < 0.001; I² = 90%, P < 0.001).

CONCLUSION

The administration of 17β-estradiol plus norethisterone acetate increases SBP and CRP concentrations and, when prescribed for less than 6 months, decreases DBP. However, despite being statistically significant, the impact of this drug combination on SBP and DBP is not clinically relevant as the variation in blood pressure values was low.

[Hypertension and menopausal hormone therapy]

Can menopausal hormone therapy (HT) be used in hypertensive women? The group of experts of the French Society of Hypertension has carried out a review of the recent literature in order to answer this question, based on the most recent scientific publications. If use of oral HT is associated with a discreet increase in blood pressure, the transdermal route seems to be safer. The first results of major randomized trials of HT had alerted to an increase in cardiovascular events and breast cancer with the use of oral HT, generally, tipping the benefit-risk balance of the deleterious side. Complementary analyzes have shown the importance of the window of intervention (less than 10 years after the menopause) and the age of the woman to start the HT. On the contrary, they have shown a significant decrease of the coronary events. For woman suffering from hypertension and important climacteric symptoms, it is important to evaluate the whole cardiovascular risk in order to decide the possibility of prescribing a HT. Thus, the group of experts proposes a prescription assistance algorithm based on the stratification of cardiovascular risk, always favoring, when it is authorized, HT by transdermal route of administration.

Effect of menopausal hormone therapy on components of the metabolic syndrome

The world population is aging, and women will spend an increasing share of their lives in a postmenopausal state that predisposes to metabolic dysfunction. Thus, the prevalence of metabolic syndrome (MetS) in women is likely to increase dramatically. This article summarizes the effects of menopause in predisposing to components of MetS including visceral obesity, dyslipidemia, type 2 diabetes (T2D) and hypertension (HTN). We also summarize the effects of menopausal hormone therapy (MHT) in reversing these metabolic alterations and discuss therapeutic advances of novel menopausal treatment on metabolic function.

Administration of 17β-estradiol to ovariectomized obese female mice reverses obesity-hypertension through an ACE2-dependent mechanism

We recently demonstrated that female mice are resistant to the development of obesity-induced hypertension through a sex hormone-dependent mechanism that involved adipose angiotensin-converting enzyme 2 (ACE2). In this study, we hypothesized that provision of 17β-estradiol (E2) to ovariectomized (OVX) high-fat (HF)-fed female hypertensive mice would reverse obesity-hypertension through an ACE2-dependent mechanism. Pilot studies defined dose-dependent effects of E2 in OVX female mice on serum E2 concentrations and uterine weights. An E2 dose of 36 μg/ml restored normal serum E2 concentrations and uterine weights. Therefore, HF-fed OVX female Ace2(+/+) and Ace2(-/-) mice were administered vehicle or E2 (36 μg/ml) for 16 wk. E2 administration significantly decreased body weights of HF-fed OVX female Ace2(+/+) and Ace2(-/-) mice of either genotype. At 15 wk, E2 administration decreased systolic blood pressure (SBP) of OVX HF-fed Ace2(+/+) but not Ace2(-/-) females during the light but not the dark cycle. E2-mediated reductions in SBP in Ace2(+/+) females were associated with significant elevations in adipose ACE2 mRNA abundance and activity and reduced plasma ANG II concentrations. In contrast to females, E2 administration had no effect on any parameter quantified in HF-fed male hypertensive mice. In 3T3-L1 adipocytes, E2 promoted ACE2 mRNA abundance through effects at estrogen receptor-α (ERα) and resulted in ERα-mediated binding at the ACE2 promoter. These results demonstrate that E2 administration to OVX females reduces obesity-induced elevations in SBP (light cycle) through an ACE2-dependent mechanism. Beneficial effects of E2 to decrease blood pressure in OVX obese females may result from stimulation of adipose ACE2.

Modification of blood pressure in postmenopausal women: role of hormone replacement therapy

The rate of hypertension increases after menopause. Whether estrogen and progesterone deficiency associated with menopause play a role in determining a worst blood pressure (BP) control is still controversial. Also, studies dealing with the administration of estrogens or hormone therapy (HT) have reported conflicting evidence. In general it seems that, despite some negative data on subgroups of later postmenopausal women obtained with oral estrogens, in particular conjugated equine estrogens (CEE), most of the data indicate neutral or beneficial effects of estrogen or HT administration on BP control of both normotensive and hypertensive women. Data obtained with ambulatory BP monitoring and with transdermal estrogens are more convincing and concordant in defining positive effect on BP control of both normotensive and hypertensive postmenopausal women. Overall progestin adjunct does not hamper the effect of estrogens. Among progestins, drospirenone, a spironolactone-derived molecule, appears to be the molecule with the best antihypertensive properties.

Sex differences in the physiology of eating

Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.

Ovariectomy and overeating palatable, energy-dense food increase subcutaneous adipose tissue more than intra-abdominal adipose tissue in rats

BACKGROUND

Menopause is associated with increased adiposity, especially increased deposition of intra-abdominal (IA) adipose tissue (AT). This differs from common or 'dietary' obesity, i.e., obesity apparently due to environmentally stimulated overeating, in which IAAT and subcutaneous (S) AT increase in similar proportions. The effect of menopause on adiposity is thought to be due to the decreased secretion of ovarian estrogens. Ovariectomy in rats and other animals is a commonly used model of menopause. It is well known that ovariectomy increases adiposity and that this can be reversed by estradiol treatment, but whether ovariectomy selectively increases IAAT has not been measured directly. Therefore, we used micro-computed tomography (microCT) to investigate this question in both chow-fed and dietary-obese rats.

METHODS

Ovariectomized, ovariectomized and estradiol treated, and sham-operated (intact) rats were fed chow or chow plus Ensure (Abbott Nutrition; n = 7/group). Total (T) AT, IAAT and SAT were measured periodically by microCT. Regional distribution of AT was expressed as IAAT as a percentage of TAT (%IAAT). Excesses in these measures were calculated with respect to chow-fed intact rats to control for normal maturational changes. Chemical analysis of fat was done in chow-fed intact and ovariectomized rats at study end. Data were analyzed by t-tests and planned comparisons.

RESULTS

Body mass, TAT, total fat mass, fat-free body mass, and %IAAT all increased in chow-fed intact rats during the 41 d study. In chow-fed rats, ovariectomy increased excess body mass, TAT, fat mass, fat-free body mass, and SAT, but had little effect on IAAT, in chow-fed rats, leading to a decrease in %IAAT. Ensure feeding markedly increased SAT, IAAT and TAT and did not significantly affect %IAAT. Ovariectomy had similar effects in Ensure-fed rats as in chow-fed rats, although less statistically reliable. Estradiol treatment prevented all the effects of ovariectomy.

CONCLUSIONS

Both ovariectomy in rats and menopause are associated with increased TAT. After ovariectomy, fat is preferentially deposited as SAT and lean body mass increases, whereas after menopause fat is preferentially deposited as IAAT and lean body mass decreases. These opposite effects of ovariectomy and menopause on regional AT distribution and lean body mass indicate that ovariectomy in rats is not a homologous model of menopause-associated changes in body composition that should be used with great caution in investigations of adiposity-related diseases.

Estrogen and hypertension

Menopause is accompanied by a dramatic rise in the prevalence of hypertension in women, suggesting a protective role of endogenous estradiol on blood pressure (BP). Both animal experimental and human clinical investigations suggest that estrogen engages several mechanisms that protect against hypertension, such as activation of the vasodilator pathway mediated by nitric oxide and prostacyclin and inhibition of the vasoconstrictor pathway mediated by the sympathetic nervous system and angiotensin. However, emerging evidence from recent clinical trials indicates a small increase, rather than decrease, in systolic BP with oral estrogen administration in postmenopausal women, without any detectable effect on diastolic BP. Mechanisms underlying this selective rise in systolic BP in postmenopausal women and oral contraceptive-induced hypertension in premenopausal women remain unknown, but the rise may be related to supraphysiologic concentration of estrogen in the liver. To date, transdermal delivery of estrogen, which avoids the first-pass hepatic metabolism of estradiol, appears to have a small BP-lowering effect in postmenopausal women and may be a safer alternative in hypertensive women.

Meta-analysis: effect of hormone-replacement therapy on components of the metabolic syndrome in postmenopausal women

AIM

To quantify the effects of hormone-replacement therapy (HRT) on components of the metabolic syndrome in postmenopausal women.

METHODS

Comprehensive searches of electronic databases were performed from April 1966 to October 2004. We included randomized controlled trials that were of at least 8 weeks duration and evaluated the effect of HRT on metabolic, inflammatory or thrombotic components. Insulin resistance was calculated by homeostasis model assessment (HOMA-IR). Subgroup analysis evaluated the effects for transdermal and oral treatment and for diabetic and non-diabetic women.

RESULTS

Pooled results of 107 trials showed that HRT reduced abdominal fat [-6.8% (CI, -11.8 to -1.9%)], HOMA-IR [-12.9% (CI, -17.1 to -8.6%)] and new-onset diabetes [relative risk 0.7 (CI, 0.6-0.9)] in women without diabetes. In women with diabetes, HRT reduced fasting glucose [-11.5% (CI, -18.0 to -5.1%)] and HOMA-IR [-35.8% (CI, -51.7 to -19.8%)]. HRT also reduced low-density lipoprotein/high-density lipoprotein cholesterol ratio [-15.7% (CI, -18.0 to -13.5%)], lipoprotein(a) [Lp(a)] [-25.0% [CI, -32.9 to -17.1%)], mean blood pressure [-1.7% (CI, -2.9 to -0.5%)], E-selectin [-17.3% (CI, -22.4 to -12.1%)], fibrinogen [-5.5% (CI, -7.8 to -3.2%)] and plasminogen activator inhibitor-1 [-25.1% (CI, -33.6 to -15.5%)]. Oral agents produced larger beneficial effects than transdermal agents, but increased C-reactive protein (CRP) [37.6% (CI, 17.4-61.3%)] and decreased protein S [-8.6% CI, -13.1 to -4.1%)], while transdermal agents had no effect.

CONCLUSIONS

HRT reduces abdominal obesity, insulin resistance, new-onset diabetes, lipids, blood pressure, adhesion molecules and procoagulant factors in women without diabetes and reduced insulin resistance and fasting glucose in women with diabetes. Oral agents adversely affected CRP and protein S, while transdermal agents had no effects.

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.

Hormone replacement therapy in Germany: Determinants and possible health-related outcomes

OBJECTIVES

To explore the determinants of hormone replacement therapy (HRT) use and possible health-related outcomes in Germany.

METHODS

827 current HRT users (age range 31-78 years, who had taken HRT products in the last 7 days before the medical interview) and 2371 age-matched nonusers were identified from five population-representative National Health Surveys performed from 1984 to 1999 in Germany. Cross-sectional comparisons between HRT users and nonusers were performed for socioeconomic factors and possible health-related outcomes. Regression models were used to obtain odds ratios of HRT use.

RESULTS

HRT use increased dramatically from 3% in 1984/1985 to 21% in 1998/1999 among German women aged 40-69. Regression analysis and comparison between HRT users and nonusers suggested that HRT use was closely associated with socioeconomic factors and personal lifestyle that may favor better health. In HRT users, however, we did not observe any health-related benefits in satisfaction with life or health. While HRT users appeared superior to nonusers with respect to the glycemic status, histories of cardiovascular diseases, despite a favorable lipid profile, occurred not less than in the group of nonusers.

CONCLUSIONS

In the settings of our cross-sectional studies in Germany HRT did not improve users' health benefits and did not show cardioprotective effects. The better glycemic status should be balanced against the higher risks of cardiovascular diseases and breast cancer.

Estradiol Induces Discordant Angiotensin and Blood Pressure Responses to Orthostasis in Healthy Postmenopausal Women

Postmenopausal estrogen replacement therapy (ERT) is reported to increase angiotensin II under resting conditions. To determine the implications of this increase for cardiovascular regulation during simulated orthostasis, blood pressure (BP), heart rate (HR), renin, angiotensinogen, angiotensin II, and aldosterone were measured at rest and during lower body negative pressure (LBNP; −10, −20, and −40 mm Hg). We studied 13 normotensive postmenopausal women (54±2 [mean±SE] years) before and after 1 month of oral estradiol 2 mg daily, and 14 premenopausal women. LBNP activated the renin-angiotensin system acutely in premenopausal but not postmenopausal women. Resting renin and aldosterone were unaffected by estradiol, whereas angiotensinogen ( P <0.001) and angiotensin II ( P <0.01) increased. Renin, aldosterone, and HR responses to LBNP (which tended to be less in postmenopausal women [ P =0.06]) were not affected by estradiol. Importantly, angiotensin II was higher on estradiol during all stages of LBNP, and increased 70% above resting values at the end of this stimulus ( P <0.05), yet BP was significantly lower, both at rest ( P <0.05) and during LBNP ( P <0.01). In summary, in normotensive postmenopausal women, estradiol increases angiotensin II, but not aldosterone, at rest and during orthostatic stress, yet lowers, rather than raises, BP under both conditions. Downregulation of vascular and adrenal responsiveness to angiotensin II may protect healthy women against this activation. Loss of such protection may elevate BP and have adverse implications for women with conditions that impair their capacity to counteract the pathological actions of angiotensin II. This may contribute to higher cardiovascular event rates reported in recent ERT trials.

Vasodilating effect of norethisterone and its 5 alpha metabolites: a novel nongenomic action

Estrogens are generally administered in hormone replacement therapy in combination with synthetic progestins. Studies of cardiovascular risk factors in postmenopausal women have shown a variety of responses according to the molecular structure of the progestin used in hormone replacement therapy schemes. The present study sets out to determine the vasoactive effects of norethisterone and its 5alpha-dihydro (5alpha-norethisterone) and -tetrahydro (3alpha,5alpha-norethisterone and 3beta,5alpha-norethisterone) metabolites in isolated precontracted rat thoracic aorta. The addition of norethisterone and 3alpha,5alpha-norethisterone in rat aorta exhibited a potent, concentration-response inhibition of noradrenaline-induced contraction, while 5alpha- and 3beta,5alpha-norethisterone had very little, if any, vasorelaxing effect. Relaxation to norethisterone and 3alpha,5alpha-norethisterone had very rapid time-courses and it was neither affected by the absence of endothelium nor by the inhibitor of nitric oxide synthase, Nomega-nitro-L-arginine methyl ester (L-NAME). The addition of specific anti-androgen, anti-progestin and anti-estrogen compounds and protein synthesis inhibitors did not preclude the vasorelaxing effect of norethisterone and its 3alpha,5alpha-reduced metabolite. The results strongly suggest that these effects are not mediated by nuclear sex steroid hormone receptors. The overall data document a novel nongenomic endothelium-independent vasorelaxing action of a 19-nor synthetic progestin and one of its A-ring-reduced derivatives.

Does the beneficial effect of HRT on endothelial function depend on lipid changes

OBJECTIVES

To determine whether improvement in endothelial function of the brachial artery observed in women treated with hormone replacement therapy (HRT) may be explained by changes in lipid profile or blood pressure, information was used obtained in a single-centre, randomised, double blind, placebo-controlled trial.

METHODS

Hundred-and-five healthy postmenopausal women, aged 50-65 years, were treated with 0.625 mg conjugated equine estrogens (CEE) combined with 2.5 mg medroxyprogesterone acetate (MPA) (CEE+MPA), 2.5 mg tibolone or placebo for 3 months. At baseline and after 3 months, endothelial function was assessed using flow-mediated dilatation (FMD) and nitro glycerine-mediated dilatation (NMD). Furthermore, lipids were measured. Multivariate linear regression analysis was applied to address the research question.

RESULTS

Treatment with CEE+MPA resulted in an improvement in FMD of 2.0% (95% CI: -0.1; 4.1). CEE/MPA reduced total cholesterol with 13% (95% CI: -18%; -7%), LDL-cholesterol with 23% (95% CI: -30%; -15%) and lipoprotein(a) (Lp(a)) with 14% (95% CI: -26%; -2%). The magnitude of the relation of CEE/MPA with endothelial function was attenuated to from 2.0 to 1.6% when change in Lp(a) was taken into account. Adjustments for other lipids or blood pressure did not attenuate the association.

CONCLUSIONS

The improvement in endothelial function in postmenopausal women treated with CEE+MPA appears to be partially mediated by change in Lp(a), and apparently not by changes in other lipids.

Administration of raloxifene does not influence 24-hour ambulatory blood pressure of postmenopausal women with osteopenia: a double-blind placebo-controlled study

OBJECTIVE

Because estrogens may decrease 24-hour blood pressure of postmenopausal women, we tested the effect of the selective estrogen receptor modulator raloxifene on ambulatory blood pressure.

STUDY DESIGN

Postmenopausal women with osteopenia who were otherwise healthy were assigned randomly in a double blind-fashion to receive placebo (n = 16 women) or raloxifene (60 mg/d, n = 16 women). Before and after 4 months, the blood pressure of each woman was monitored every 30 minutes for 41 hours with the use of an ambulatory device.

RESULTS

Similar to the placebo outcome, the raloxifene administration did not modify 24-hour daytime (7 AM -11 PM) and nighttime (11 PM -7 AM) blood pressure and heart rate values. Day-night differences and the 24-hour rhythmic variation of mean blood pressure, which was evaluated by cosinor analysis, were also not affected by placebo or by raloxifene.

CONCLUSION

Raloxifene does not influence 24-hour blood pressure of postmenopausal women. These data are reassuring for the cardiovascular safety of the long-term raloxifene administration.

Hormone replacement therapy does not affect 24-h ambulatory blood pressure in healthy non-smoking postmenopausal women

OBJECTIVE

Controversies surrounding the physiological effects of hormone replacement therapy (HRT) currently lie at the forefront of medicine. Important interindividual factors that affect blood pressure, such as smoking, body mass and sodium intake, may account for the conflicting findings seen in studies examining the effects of HRT on blood pressure.

DESIGN

The study was a randomized, double-blind, placebo-controlled trial.

METHODS

The effect of combination HRT and estrogen-only replacement therapy (ERT) on ambulatory blood pressure was examined in a sample of 46 healthy, normotensive, non-smoking, non-obese postmenopausal women between 45 and 65 years of age. Twenty-four hour urinary sodium excretion was examined prior to and following treatment. The women were randomized to 3 months' treatment with HRT, ERT or placebo.

RESULTS

After treatment, there were no significant effects of either HRT or ERT on daytime or night-time systolic or diastolic blood pressure. Sodium excretion was similar across the groups. There were no effects of treatment on night-time blood pressure dipping.

CONCLUSIONS

The findings from this prospective treatment study support the conclusion that HRT has no significant effect on daytime or night-time blood pressure in a sample of healthy, non-smoking postmenopausal women.

Hormone replacement therapy and hypertension

Hypertension, particularly systolic hypertension, affects postmenopausal women and is an important risk factor for cardiovascular disease in this group. In the last year, several papers have better defined the mechanisms by which hormone replacement therapy influences blood pressure in postmenopausal women, including effects on nitric oxide, angiotensin II and vascular stiffness (compliance). Currently, data concerning the influence of hormone replacement therapy on blood pressure in postmenopausal women are inconclusive because of the limitations of published studies. It is clear, however, that hypertension is not a contraindication to starting hormone replacement therapy.