Chapter 9

The Climacteric, Menopause and HRT

The climacteric

The climacteric is the period of time which precedes the final cessation of menstruation, and may last for 1-10 years. It indicates a gradual decline in ovarian function and reproductive capacity during the late 30s and early 40s, even in women with regular menstrual function. In contrast to puberty, which represents the development of reproductive capability, the climacteric signifies the beginning of the end of that capability.

Both ovarian and hypothalamic ageing have been documented as causes for the onset of the climacteric period. Few related endocrine changes can be seen during the late thirties and early forties:

1.   The earliest changes reflect the gradual decline in the number of preantral and small antral follicles. The level of antimullerian hormone drops first, followed after some time by reduction in inhibin B production. This later change reduces the inhibitory effects on the hypothalamus and pituitary gland, leading to increased production of follicle stimulating hormone (FSH). There are no significant changes in the levels of oestradiol, inhibin A or luteinising hormone (LH) at this early stage.

2.  Higher levels of FSH start rising earlier during the luteal phase of the cycle, resulting in early recruitment of follicles for the subsequent cycle, even before the start of menstruation in the current one. Accordingly, the recruited follicle will be more advanced during the early follicular phase of the subsequent cycle, and will only need a short period of time to attain full maturation. This leads to a short follicular phase and polymenorrhoea, which are early signs of incipient ovarian failure. The level of oestrogen may be high during the whole cycle in some cases, with the possibility of luteal phase dysfunction. The increase in FSH level usually affects few cycles only initially. More cycles will be slowly affected, till ultimately a high FSH level becomes detectable in all cycles. This can still happen while the patient has regular menstruation.

3.  With further decrease in the number of follicles, excessive FSH is produced coupled with slower response by the remaining less sensitive ones. This results in a longer follicular phase, inadequate ovulation, and occasionally dysfunctional uterine bleeding. The cycles become less frequent and anovulatory over time, before total cessation of menstruation.

Coinciding with the decline in oocytes numbers, cytogenetic studies and in vitro fertilisation treatment cycles showed the following problems:

• Abnormal arrangement of the chromosomes on the myotic spindle in metaphase II oocytes;
• Increased incidence of aneuploidy in the resulting embryos.

Independent of ovarian aging, changes in the negative feedback mechanism due to hypothalamic ageing have also been suspected to occur in regularly menstruating women in their late 30s and early 40s. This can initiate or at least be a contributing factor to the high FSH levels documented during the early follicular phase in these women. Certain observations have been mentioned in support of this point

Changes in the level of inhibin B and oestradiol do not explain changes in the level of FSH in all women in their late thirties and early forties who have regular menstrual cycles; 

The occurrence of hot flushes in women between the ages of 35-40 years despite having regular cycles and normal oestradiol level; 

Failure of the pituitary gland to respond to an oestrogen challenge test with LH surge is a common observation in women during the climacteric period (1);

Reduced LH pulse frequency and increased pulse width during the mid follicular phase in regularly menstruating women in their forties can be related to changes in the negative feedback mechanism, and partly explain the age related changes in reproductive potential (2).

The menopause

Natural menopause is a term used in retrospect to indicate the last menstruation, one year after its occurrence in women >45 years of age. In contrast to puberty, the age at menopause has not changed over the last century and remained stable in different communities and families. In western countries, the average age at the menopause is 51 years. Permanent cessation of menstruation before the age of 40 or 45 years is termed premature and early menopause respectively. Nonetheless, the term premature menopause is not acceptable by many patients, and can be medically incorrect as will be discussed in Chapter 10. On the other hand, surgical menopause can occur when the ovaries are removed, at any time, before the average age of natural menopause.

Certain factors have been documented to affect the age at which the natural menopause may occur. A woman’s age at menopause is very much affected by the age her mother reached the menopause, reflecting the importance of genetics in this respect. This familial trait has been supported by twins’ studies. Smoking, lower educational attainment, being separated, divorced or widowed, unemployment and history of heart disease have been reported to be independently associated with earlier natural menopause. On the other hand, parity, prior use of oral contraceptives and Japanese race/ethnicity were associated with a later age at natural menopause (3). Similarly, a multiethnic study which involved 103,893 women in 2008 (4) showed that race/ethnicity was a significant independent predictor of the timing of natural menopause. All other factors including smoking, age at menarche, parity and body mass index did not significantly alter the effect of race/ethnicity-specific hazard ratio. This is agreeable with a previous report which showed that all lifestyle and reproductive factors explained the difference in age at natural menopause in less than 10% of the cases, after studying 2182 twin pairs (5). Accordingly single ethnic group studies are liable to miss this important effect of race/ethnic origin.

Despite all the research conducted in this field of reproductive endocrinology, there are no set reliable biochemical criteria to predict the exact age at the menopause. Measuring early follicular phase FSH levels is useless in this respect, as high levels can be detected many years before the menopause. This test may be useful in showing a low ovarian reserve and fertility potential, when a high level is reported. Even in this context, a normal level in women in their late thirties does not indicate normal fertility potential. The following general points have been found to be helpful in predicting an early menopause:

Maternal history of early menopause;

Twelve or more months of amenorrhoea at or beyond the age of 45 years is associated with 90% chance of no further  menstruation;

History of 3-11 months of amenorrhoea at or beyond the age of 45 years is associated with 95% chance of the menopause within 4 years. 

Poor response to controlled ovarian hyperstimulation at the first in vitro fertilisation (IVF) treatment cycle has been associated with a higher risk of early menopause (<46 years), in comparison to women who developed more than 3 follicles (6, 7).

Endocrine changes associated with the natural menopause

Androgens

The menopause is followed by a hypoestrogenic state due to ovarian failure, with peripheral adipose tissue producing a major fraction of the circulating oestrone, which is the main oestrogen in this age group. This depends on the BMI of the individual patient. There is little progressive decline in adrenal androgens production after the menopause, following the maximum decline which occurs between the ages of 20 - 40 years. This results in 70-80% reduction in dehydroepiandrosterone (DHEA) production rate by the age of 70 years (8). This decline in adrenal androgens production is not matched by any decline in cortisol production as reported by Liu et al in 1990 (9). They found decreased DHEA/17-hydroxypregnenolone and androsdenedione/17-hydroxyprogestgesgterone ratios which they attributed to decreased 17, 20-desmolase enzymatic activity. Furthermore, they attributed the decline in DHEA blood levels to reduced pulse amplitude without any changes in its circadian (daily) or ultradian (pulse frequency) secretion patterns. On the other hand, ovarian androgens production normally decline over the reproductive years with the maximum decline rate being just before the menopause (10). There is 50% reduction of the daily production rate of androstenedione mainly from the ovaries, with the adrenals being the main source in postmenopausal women.  There is also a small decline in the level of sex hormone biding globulin (SHBG), but not significant enough to affect the free androgen index. DHEA forms the main circulating androgen during the postmenopausal period, and it is readily converted to oestrogen and testosterone. This forms the theoretical background for using it as a food supplement after the menopause to provide a form of hormone replacement therapy, and as an anti-aging agent as well.

Thyroid indices

Thyroid gland dysfunction is also more frequent during the late reproductive years, and after the menopause. Women are almost 8 times more likely to have such problems in comparison to men of the same age group. Clinical and subclinical thyroid diseases have been reported in 2.4% and 23.2% of postmenopausal women respectively by Schindler in 2003 (1). Among those with the subclinical disease, 73.8% were hypothyroid and 26.2% were hyperthyroid. Accordingly, this same author recommended routine screening of thyroid function in the climacteric period to determine subclinical thyroid diseases. This is especially so as subclinical hypothyroidism may be associated with dislipidaemia in the form of high total cholesterol, high low density lipoprotein (LPL) cholesterol, and low high density lipoprotein (HDL) cholesterol. Such a deranged lipid profile can increase the risk of cardiovascular problems in these patients. The risk is also increased because of the reduced oestrogen / androgen ratio. Oestrogen medication can affect the thyroid status by increasing the level of thyroxine binding globulin (TBG); hence reducing the level of free thyroxine in circulation. This may aggravate problems in women with subclinical hypothyroidism. Conversely, transdermal HRT has no similar effect on TBG, as it has no first hepatic pass and should be used by patients with hypothyroidism on HRT. On the other hand, hyperthyroidism has a detrimental effect on bone density, and can induce osteoporosis. This effect has been documented even in healthy postmenopausal women with persistently low normal thyroid stimulation hormone (TSH), by Kim et al in 2006 (12). The same authors suggested that low normal TSH levels may not be physiological for postmenopausal women, and during treatment of hypothyroidism, and may not be adequate for avoiding osteoporosis.

Changes in LH dynamics

Beside the changes in FSH level alluded to before, more subtle changes have also been documented in LH secretion. Increased LH pulse frequency and amplitude have been documented during the luteal phase of the cycle during the late reproductive years. Different reports documented changes or no changes during the follicular phase. Nevertheless, the evidence is more compelling towards decreased LH pulse frequency and amplitude during the mid follicular phase in older women during their reproductive years (2). This was attributed on one side to ageing or enhanced hypothalamic-pituitary negative feedback mechanism, or to increased oestradiol level at that point of the cycle. This later point can be a reflection of the rapid recruitment and larger follicles occasionally seen during the early part of the cycle in women with polymenorrhoea, as alluded to before. Eventually, elevated LH levels throughout the cycle are observed in ovulatory women by the age of 45 years (13).

Changes in body habitat

A noticeable observation is the change in body composition during the late climacteric period, and after the menopause. This is manifested in the form of central obesity which may be due to:

1. Reduced oestrogen / androgen ratio favours an android or central body fat deposition, which can be reversed by oestrogen medication.

2.    Decreased energy expenditure due to

1. Reduced resting metabolic rate;
2. Decreased physical activity;
3. Higher risk of hypothyroidism.

Postmenopausal symptoms

Following the menopause oestrogen withdrawal symptoms can be acute, intermediate or delayed. The most distressing symptoms are the acute ones which can affect the patients’ quality of life, but the delayed ones carry more long term medical risks.

Acute symptoms

Nearly 80% of postmenopausal women experience acute symptoms which can be vasomotor or psychological in nature, but not all of them seek medical advice. The two main vasomotor symptoms are hot flushes and night sweats, but many women may present with headaches, palpitations and fainting attacks. A wide range of psychological symptoms can be seen including depressed mood, sleep disturbance, mood swings, lack of concentration, loss of memory, fatigue and anxiety state. Many younger women in their late thirties and early forties, who have regular menstrual cycles, may also have oestrogen deficiency symptoms mainly premenstrually. It is important to exclude other medical conditions which can give similar symptoms, especially in patients not responsive to HRT. Such conditions include anaemia, sleep apnoea, panic attacks and hyperventilation, thyroid dysfunction, clinical depression, diabetic autoimmune dysfunction, carcinoid syndrome and phaeochromocytoma.

Hot flushes make the most important and distressing acute vasomotor symptom, which can affect patients’ lives negatively in many ways. They may be associated with night sweats which disturb the patient’s sleeping pattern, leading to fatigue and inability to perform every day life duties. Nearly 20% of women can be badly affected and will need medical help. Though they are mainly related to oestrogen withdrawal, oestrogen levels have not been found to be significantly different in women with and without hot flushes (14). Furthermore, stimulation of the sympathetic nervous system can also start an episode of hot flushes, indicating its importance in this respect. In fact increased catecholamines production in the brain has been documented in women during episodes of hot flushes (15). Sociocultural factors are most likely involved as well, as the incidence of hot flushes was reported as 82% in American women (16), 60% in Swedish women (17), with yet lower figures in developing countries (18). More recent publications almost duplicated this trend. The effect of ethnic origin has also been shown by an article published by Monterrosa et al in 2009 (19). They found that impairment of quality of life in postmenopausal women varied according to race in different Columbian groups. Urogenital symptoms were more severe in indigenous and black women, whereas somatic and psychological symptoms were more severe in Hispanics.

Each hot flushing episode may last 1-5 minutes, but can be longer. The patient feels warmth or heat in the face, shoulders and neck area depending on the severity of the attack. This may be associated with reddening of the skin and profuse sweating, which corresponds to the distribution of the cervical sympathetic trunk. Such visible changes are usually seen in approximately 50% of the patients. It is usually followed by feeling cold and shivering. The intensity of the symptoms varies between women, and at different times in the same woman. In general, surgical menopause is usually associated with more severe symptoms than the natural one. Prolonged and repeated flushing episodes may lead to telangiectasia and classical rosacea of the face (20). Occasionally, symptoms may follow intake of spicy food or caffeine, hot bath or shower, cigarette smoking, alcohol consumption, and anxiety state. Women perception of the menopause and its implications on health, family relations and sexuality depends on their cultural background and own personality. This may have direct bearing on their coping abilities, and how they react to oestrogen deficiency symptoms. Other predisposing factors include family history of hot flushes, and a high body mass index. Episodic hot flushes may last for up to 5 years in 65%, 6 – 10 years in about 25% and >11 years in 10% of affected postmenopausal women. 

The exact causes for hot flushes are still speculative and many factors have been implicated. In a recent review in 2009, Andrikoula et al (21) discussed few possible factors related to women predisposition to hot flushes.

• The mean blood pressure was found to be higher in women who had hot flushes than in those who did not have similar episodes. This is despite of the fact that the blood pressure may drop during the episodes themselves.
• Furthermore, postmenopausal women with hot flushes were found to have higher electrodermal activity during stress.
• Lower total plasma antioxidant activity, lower concentration of reduced sulfhydryl groups, and higher plasma concentration of lipoperoxides have also been found in women who had hot flushes, compared to those who were not similarly affected (22).

All these factors are known to increase cardiovascular disease risks in women with hot flushes. A recent report by the Women’s Health Across the Nation Heart Study (23) showed that women who had hot flushes had reduced brachial artery flow-mediated dilation, and greater aortic calcification. 

Control of body temperature

Body temperature is controlled by thermoregulatory means of neuroendocrine and autonomic structures that keep the core body temperature within certain range of threshold values (24). The upper or ‘sweating’ threshold is involved with release of heat, and the lower or ‘shivering’ threshold with heat conservation and renewed production. These thresholds maintain the thermoneutral zone (25), which is regulated by different parts of the central nervous system (CNS), including the spinal cord, brain stem, limbic system and the preoptic area of the hypothalamus. The initial impulses about body core temperature are sent by sensors found in different parts of the body, including the spinal cord, intra-abdominal veins and the gastrointestinal tract. The final role is played by peripheral blood vessels which dilate or constrict to lose or preserve heat respectively, in response to impulses form the CNS. This system is modulated by serotonergic and noradrenergic impulses. Hot flushes occur when the core body temperature increases above the sweating threshold, which leads to peripheral vasodilatation with increased blood flow to lose heat. On the other hand, when the core body temperature falls below the shivering threshold, peripheral vasoconstriction leads to heat conservation within the body. The question to ask now is why some and not all women have hot flushes, and to different degrees of intensity? It has been suggested that women prone to hot flushes have a narrow thermoregulatory zone (core body temperature range), at which neither sweating nor shivering occurs (24). This zone may be further narrowed by sympathetic stimulation, which explains why stressful stimuli bring about hot flushes. On the other hand, drugs that suppress the sympathetic tone widen this zone. A similar effect is also caused by oestradiol. (26). The differential diagnosis of vasomotor symptoms includes anxiety state, thyrotoxicosis, carcinoid syndrome and phaeochromocytoma. Accordingly, usual medical acuity should be exercised to exclude these possibilities before assuming oestrogen deficiency symptoms, especially in younger women. Older symptomatic women not responding to HRT should also be investigated for these possibilities. Twenty four hours urine 5-HIAA (5-hydroxyindolacetic acid) should be measured in suspected cases of carcinoid syndrome. False negative results are not uncommon, as the excretion rate is variable, and the test may need to be repeated. On the other hand, false high urine 5-HIAA can be caused by certain types of food including bananas, pineapples, coffee and chocolates. Suspected cases of phaeochromocytoma should be investigated with plasma and 24 hour urine catecholamines and metanephrines. These tests have got certain limitations. Catecholamines have got short half-life which may lead to a false negative result if a single assay is performed during intervals between surges of high blood pressure (27). Accordingly, measurement of metanephrines is preferred as they act as direct tumour markers and indicators of catecholamine release (28). Inaccuracy of 24 hour urine collection can lead to false positive and false negative results, if the collection time exceeded or was less than 24 hours respectively. In a recent study Lenders et al found plasma metanephrines measurement had 100% sensitivity for diagnosing phaeochromocytoma, compared to 89% for the urinary products (29). This discrepancy caused by problems with urine collection was corrected by measuring the urinary metanephrines-to-creatinine ratio, which improved the sensitivity to 100% (28).

Intermediate symptoms

These symptoms usually occur within 1-3 years after the menopause, and about 50% of women may have them by the 5^th – 8^th year. They are mainly related to loss of skin and joints collagen and urogenital atrophy; the later one being more distressing.

Prolonged lack of oestrogen can lead to atrophy of the vaginal skin and the area of the vestibule, and may affect 60% of postmenopausal women. This figure may be an underestimation of the real incidence, as it is usually an under diagnosed and inadequately treated condition (30). It can lead to burning sensation, irritation and rawness which may affect sexual relationship. Superficial dyspareunia can be a real problem, which can progress to vaginismus, loss of libido and apareunia. A figure of 32% has been quoted for women who lost sexual relations because of vaginal skin dryness and atrophy (31). The problem can be magnified by atrophy of the epithelium covering the urethra and trigone, as they share an embryonic origin with the lower vagina from the urogenital sinus. This can lead to increased frequency of micturition, and other voiding problems. Unlike hot flushes, symptoms of vaginal atrophy tend to get worse with time and may show for the first time 10 years after the menopause. Some statistics have been reported by Dennerstein et al in 2000 (32) in relation to the development of vaginal dryness. They quoted an incidence of 3% in perimenopausal women, and 21% and 47% incidence one and three years after the menopause respectively.

Sexual dysfunction in mid-life women has also been positively correlated to depressive symptoms and poor general health. It is remarkable that women who showed higher total testosterone and free testosterone index, but not oestrogen, had better sexual drive and relationship (33). This may justify the use of testosterone supplements to improve this aspect of patients’ lives. Intrinsa (Procter and Gamble) transdermal patches can be used every 3-4 days, and provide 300 µg testosterone every day. Patients should be warned against androgenic side effects which can be permanent. Other adverse effects include migraine headaches, insomnia, weight gain and breast tenderness.

Changes in collagen fibres can affect tendons tensile strength, leading to painful joints on movement. This is usually a neglected problem, and occasionally a diagnosis of arthritis is made. Certain women are liable to lose their skin moisture and elasticity more than others, which results in wrinkles and premature ageing. This can have devastating psychological effects. Skin ageing is usually affected by many factors being genetic, environmental or hormonal. Natural or intrinsic ageing is usually characterised by smooth pale finely wrinkled skin, and dryness. On the other hand, photo-ageing which follows excessive exposure to the sun is characterised by severe deep wrinkles, as well as pigmentation changes, such as solar lentigo and mottled pigmentation (34). A woman in her 50s may look much older than her siblings, especially those on HRT which is known to preserve skin moisture, as well as collagen and elastic tissues integrity. Nevertheless, the last author (34) questioned the use of HRT for the sole indication to prevent or reverse skin ageing. This view may well change with time, especially as topical conjugated oestrogen cream medication resulted in significant improvement of fine facial wrinkles in postmenopausal women (35). Beside the cosmetic issues, decrease in skin collagen and thickness have been found to correspond to reduction in bone mineral density (36). Accordingly, it can be used as an early indication for investigating bone density, to pre-empt future osteoporosis.

Long term effects of oestrogen deficiency

The two main problems in this group are osteoporosis and coronary heart disease (CHD). The mostly affected bones are the femur neck and vertebral column. Long term hypo-oestrogenism can be complicated with femoral neck and vertebral crush fractures, as well as wrist and Colles fractures. It is estimated that 1 in 7 postmenopausal women sustain a fractured neck of femur. Furthermore, 40-50% will sustain such a fracture before the age of 75 years. The serious point about these statistics is that about 3 of 5 postmenopausal women will not lead an independent life after a fractured hip, and there is 20% mortality within one year. This is on top of the large expenses necessary to care for these women. With advancing years after the menopause, osteoporosis gets worse but more so in the following groups of patients:

• Family history of osteoporosis;
• Low peak bone mass by the age of 20 years;
• Early age at the menopause;
• Low production of oestrone by adipose tissue in underweight patients;
• Cigarettes smoking;
• Excessive alcohol intake;
• Sedentary life style;
• Prolonged used of corticosteroids;
• Subclinical hyperthyroidism.

The relationship between osteoporosis and hypo-oestrogenism can be related to excessive parathyroid hormone activity, and reduced calcitonin secretion with increased osteoclastic activity. Oestrogen counteracts parathyroid hormone and 1, 25 dihydro vitamin D bone resorbing action. It also stimulates calcitonin secretion. On the other hand, oestrogen receptors are found in bone. Accordingly, it can act directly by increasing proliferation of osteoblasts through production of IGF-1 and TGF-β, and inhibits osteoclasts differentiation from their bone marrow precursors.

The other important effect of long term oestrogen deficiency is on cardiovascular disease (CVD), which accounts for 1 in 4 deaths in women after the age of 50 years.  There are more deaths from breast cancer in women under the age of 50 years than from strokes and ischaemic heart disease combined. This pattern is reversed after the menopause. Furthermore, the life time risk of death from heart attacks, stroke and hip fractures is greater than the risk of death from breast cancer. The risk of CVD increases with time, irrespective of the age when the menopause occurred. However, endothelial-dependent vasodilatation usually deteriorates after the menopause and attains similar levels to older men by the 6^th decade of life (37). This follows a significant decline in the oestrogen protective effect on vascular endothelial function, which is a critical factor in causing CVD. Oestrogen modulates endothelial function by enhancing nitrous oxide (NO) release and by promoting vasodilatation (38). The postmenopausal state is also associated with higher levels of inflammation markers including interleukin-6 (IL-6) and tumour necrosis factor-a (TNF-a), as well as reduced antioxidants which indicate increased oxidative stress (39). Many other factors increase the risk of CVD including obesity, high blood pressure, diabetes mellitus, smoking, raised triglycerides and LDL cholesterol and reduced HDL cholesterol levels.

Management

It is clear that quality of life can be affected in different ways at different stages of the climacteric and postmenopausal periods. This is a distressing situation, as more women now live well beyond their 70^th birthday. Such a long life is associated with increased risk of postmenopausal medical problems. Central obesity and its detrimental effects on CVD have already been alluded to. On the other hand, there is a tendency for blood pressure to increase with age in women. By the age of 69 years, almost 80% of women have hypertension (40). Even a high normal blood pressure of 140/90 is associated with increased risk of CVD, and small reductions in blood pressure result in major reduction in CVD risk. In mathematical terms, it has been suggested that reduction of 10 mm Hg in systolic pressure during the menopausal transition results in 25% reduction in cardiovascular events. It is evident that many factors can be addressed to reduce the risk of CVD through changes in life style, loss of weight, regular exercise, strict control of diabetes and high blood pressure.

It is unfortunate that a lot of confusion has clouded the management of the menopause with HRT, because of much publicised increased risk of breast cancer, and coronary heart disease. This is partly due to the initial conclusions drawn from the Women Health Initiative Study (41), and other similar publications. Unfortunately, the medical profession fell into the traps set by the Media, and magnified the negative points in these reports, in spite of the known flaws with those studies. Many young women, even those with premature ovarian failure have been deprived of HRT, and are leading miserable lives. Alternative remedies of unquantified benefits found the right void in the market to fill, and understandably their unproven alleged safety has been magnified by the selling vendors.

Many well balanced articles have been published to put things into their real perspective in relation to HRT use. In 2008 an expert group (42) published important key practice points, in relation to HRT use. They suggested that the risks involved with HRT should be conveyed in absolute numbers rather than percentages. Furthermore, they recommended HRT for young postmenopausal women to maintain quality of life, and for primary prevention of cardiovascular risks. They even recommended testosterone supplementation for women with hypoactive sexual desire disorder (HSDD) and unexplained tiredness. Regarding breast cancer risk, they suggested that young postmenopausal women who are about to start HRT for the first time should be counselled that breast cancer risk does not increase for the first 7 years. They also stated that unopposed oestrogen replacement therapy for hysterectomised women does not increase breast cancer risk, and may even lead to a small reduction in the risk. On the other hand, they stated that phytoestrogens and herbs are less effective than classical HRT, and their quality control is questionable. It is important here to reiterate the beneficial antioxidant and anti-inflammatory effects of oestrogen alluded to before. Furthermore, adequate exposure to oestrogen during the menopause transition is believed to reduce or even prevent vascular endothelial dysfunction by the expression of functioning oestrogen receptors a (ERa) which are mediators of nitrous oxide release (39).

Transdermal testosterone

The benefit of transdermal testosterone system (TTS) in a low daily dose of 300 µg has been confirmed by many clinical trials without any significant virilizing effects even after 2 years of use. However, its effect on metabolism, the breasts or endometrium is not elucidated yet as discussed by Rymer et al in 2010 (4£). Appropriate patient’s selection is also important, to reduce the unwanted complications. It is indicated mainly for women with hypoactive sexual desire disorder as part of a total management plan, as the condition itself is multifactorial. It may be related to psychiatric conditions or temporary psychological issues, medical conditions and the use of pharmacological agents. Reduced sexual desire disorder is more common in women who had surgical menopause compared to premenopausal women and those who had natural menopause (44). Oral testosterone formulations should be avoided, as they undergo first-pass hepatic metabolism. Prolonged use may lead to hepatic dysfuncion, hepatomas and hepatocelluar carcinoma. Oral medication has also been shown to reduce high density lipoproteins (HDL), and increases triglycerides blood levels in oestrogen treated women. It is good practice to perform liver function tests and a fasting lipid profile before starting testosterone mediction, and at regular intervals while on medication. It has also been stated that testosterone medication could not be recommended without concomitant oestrogen therapy (45).

Contraindication to HRT use

HRT is contraindicated in the following conditions, and other methods should be considered instead:

·       Active liver disease;

·       Undiagnosed genital bleeding;

·       Current, past or suspected breast cancer;

·       Oestrogen dependent malignancy e.g. endometrial carcinoma;

·       Endometrial hyperplasia;

·       Active or recent venous or arterial thromboembolic disease;

·       Untreated hypertension;

·       Porphyria cutanea tarda.

In these circumstances another non-hormonal medication should be used:

• Clonidine, which is an a adrenergic agonist, was the only alternative available in the past. It is no longer a second line medication, because of its many side effects which include hypotension, fatigue, drowsiness, insomnia, constipation and dry mouth.
• Selective serotonin reuptake inhibitors (SSRI) have proved useful, in combination with noradrenaline reuptake inhibitors (SNRI). Venlafaxine proved useful in relieving vasomotor symptoms and low mood without having a sedative effect, but is not useful in relation to bone density preservation. It can be started in a dose of 37.5 mg every day. With inadequate response the dose can be stepped up to 75 mg daily. This may reduce side effects and improves compliance. The dose should also be tapered before stopping the drug altogether.
• Gabapentin has also been shown to improve vasomotor symptoms. This was a coincidental observation in postmenopausal women who had chemotherapy for breast cancer. This observation has since been followed prospectively in controlled studies. Guttoso et al in 2003 found no difference between gabapentin and conjugated equine oestrogens in the management of hot flushes (46). A similar conclusion has been reached by Aguirre et al in 2010 who found gabapentin in a daily dose of 600 mg to be as effective as low dose transdermal oestradiol (25 µg/day) in controlling moderate to severe hot flushes (47)
• Anti depressants can be used when clinical depression is diagnosed.
• Phytoestrogens, on the other hand, can improve menopausal symptoms, but their safety in patients with contraindications to classical HRT has not been studied.

DHEA

The use of DHEA as a form of nutritional HRT supplement has been alluded to before. It has been used in daily doses of 25 mg and 50 mg by Genazzani et al (6) and Stomati et al (48), respectively. They reported increased blood levels of oestrogens, DHEA, androstenedione, testosterone, allopregnenolone, and b-endorphins in postmenopausal women. Beside the beneficial effects of the steroidal hormones, allopregnenolone and b-endorphins have anxiolytic effect and promote relaxation and feeling of wellbeing. Using the lower dose of 25 mg/day resulted in significant improvement in vasomotor symptoms and psychological disturbances during the early and late postmenopausal years respectively (6). Furthermore, there were no detrimental endometrial changes even after 12 months of medication, as shown by thin endometrial echoes during repeated ultrasound scan examinations. The exact effective and safe daily dose of DHEA is not yet established. A case report published by Sahelian and Borken in 1998 reported cardiac arrhythmia as a side effect of DHEA when used in a daily dose of 25 mg (49). Another important drawback of this medication is that monitoring blood or saliva DHEA levels do not reflect its biological effects at tissue level. Even a more important fact is that a Cochrane review published in 2006 found little evidence from controlled studies to support a beneficial effect of DHEA supplementation on cognitive function of non-demented middle-aged or elderly people (50). However, it did not find consistent evidence of any adverse effects. Currently doses of 5-50 mg tablets are marketed through various venues including the Internet, with no medical control.

Contested recommendations

It has been recommended that HRT should be used in the smallest effective dose for the shortest period of time. Setting a short time limit has been criticised as false, and treatment should be continued as long as it is needed by the patient. Nevertheless, regular reassessment of the indication and the dose should be done on an annual basis, at least. The minimum effective daily starting doses for oral oestradiol have been reported as 0.5-1.0 mg, and 0.3-0.45 mg for conjugated equine oestrogen. The equivalent doses for transdermal oestradiol patches and oestradiol gel are 25.0-37.5 µg, and 0.5-1.0 mg respectively. Assessment of response should be done after 2 – 3 months. About 20% of patients may not have an adequate response, and the dose will need to be increased. The route of administration should be carefully selected. Patients with high triglycerides blood levels and migraine headaches should avoid oral HRT, and should have transdermal medication instead.

It is noticeable that the recommendations put forward by many official bodies regarding the use of HRT after the publication of the WHI study (41) have not been changed, despite the critical reviews and the published evidence against many of these recommendations. This is especially so for the inappropriate conclusions regarding cardiovascular disease and breast cancer, as the results had been generated from older postmenopausal women above the age of 60 years. In a very critical editorial, Pines et al (4) criticised the planning and the initial conclusions drawn from the WHI study (41), which lead to dramatic decline in the number of women using HRT. Unfortunately, the extrapolation of results from older women and their generalisation to symptomatic younger patients who have just gone through the menopause has lead to a sharp decline in the number of women using HRT. Many other reviews criticised the study on similar grounds. The same authors (51) came to the conclusion that women should be reassured regarding oestrogen therapy as safe when initiated near the menopause, and under the age of 60 years. There is also a potential to improve quality of life in symptomatic women, and reduce their risk of future heart disease and premature death. Furthermore, they recommended that symptomatic perimenopausal women with no inherent breast cancer risk factors can safely use HRT for 7 years.

Thromboembolic risks

The only sticky point concerns an increased risk of thromboembolism with age and obesity in postmenopausal women using oral HRT. Younger overweight patients are at risk as well. To put things into perspective, the number of additional cases of venous thromboembolism over a 5-year period was 2-6 per thousand women aged 50-59 years, as reported by the WHI study itself (41). This increase was seen only during the first 2 years of oral medication, in women with a body mass index above 25 kg/m². Accordingly, women with such body habitat who develop vasomotor symptoms should have thorough counselling, and other non hormonal medications can be used instead. Nonetheless, the quality of life should always be considered in the equation when counselling these patients. Transdermal HRT can be used in cases with severe symptoms not responsive to other medications. Production of vitamin K-dependent coagulation factors by the liver is directly correlated to the dose of oral oestrogen used. Furthermore, oral medication can induce activated protein C resistance in some patients. Both effects were not seen in patients using transdermal oestrogen HRT. Moreover, oral oestrogens reduce the level of anti-thrombin III which inhibits activated coagulation factors (52). A recent review of the available biochemical and clinical data by Birge in 2008 (532) suggested that women on low dose transdermal oestrogen medication are not at increased risk of cardiovascular disease, stroke, venous thrombotic disease, or even breast cancer. In fact Canonico et al in 2007 showed a decrease in venous thromboembolism in patients using transdermal menopausal hormone replacement therapy (54). However there was no decrease in acute CHD attacks in women with angiographically demonstrable ischaemic heart disease (55).

Endometrial cancer risk

The risk of endometrial cancer is a real one in women using unopposed oestrogen replacement therapy (ERT). Accordingly, the endometrium should always be protected with 12-13 days of a progestogen medication. Alternatively, the mirena system is a good alternative for this purpose, with the high local concentration of levonorgestrel. This is especially useful, as continuous ERT can be given without a break, especially for patients who developed bad vasomotor symptoms during the HRT free one week episode. It is important to mention here that a case control study published in 2010 showed increased risk of breast cancer, whether the mirena system was used alone or together with ERT (56). This is a significant finding which could sway many gynaecologists and patients from recommending and using the mirena system respectively. However, more studies are needed to confirm this finding. Doctors may start looking again to alternative progestogens to use. It has been mentioned that progestogens derived from natural progesterone and dydrogesterone have lower risk for promoting breast cancer than synthetic progestogens derived from C21 progesterone and 19-nortestosterone (57), used during combined therapy.

Younger symptomatic women, especially those with premature ovarian failure, usually need a higher dose of oestrogen compared to patients who went through the natural menopause. For non smoker healthy patients in this group, an oral contraceptive pill will be a reasonable option to provide the necessary oestrogen replacement, and to maintain regular withdrawal bleeding. Older women can have dedicated HRT combined medication, either orally or in a transdermal form. The later form is more physiological as it does not have the first hepatic pass, in contrast to the oral route. Women on continuous combined HRT are more at risk of having breakthrough bleeding, which may cause alarm especially in older postmenopausal women. Accordingly, they should have endometrial assessment if they continue to have irregular bleeding for the first 6 months of treatment, or if they develop abnormal uterine bleeding for the first time after long uneventful use of HRT (58).

The ideal drug to deal with postmenopausal medical problems should have the following characteristics, as discussed in the literature:

• It causes no detrimental haematological or biochemical changes;
• It controls all the acute and intermediate symptoms effectively;
• It does not lose efficacy through tachyphylaxis after prolonged use;
• It has good safety margin when used for long periods of time;
• It does not cause abnormal uterine bleeding;
• It reduces risks of cardiovascular diseases;
• It does not increase the risk of uterine cancer;
• It does not increase breast cancer rate;
• It prevents osteoporosis and reduces bone fracture risks.

Obviously, none of the available drugs has all these attributes, and we should make the best out of what is available to us currently. Most important is the fact that hypo-oestrogenic women should not be denied medical help and left to suffer because of our current misinformation regarding the magnitude of the potential risks involved. Patients should be involved in decision making, because quality of life is a personal choice. This is especially so, as the medical evidence against using HRT is far from compelling.

Selective oestrogen receptor modulators

Selective oestrogen receptor modulators (SERM) are non steroidal compounds which have an oestrogenic effect on one or more target tissues, with anti oestrogenic effect on others. The first generation SERM tamoxifen is widely used for the treatment of breast cancer. Other second generation drugs have been produced for the treatment of osteoporosis, especially in patients over the age of 60 years. However, they have similar thromboembolic risks like oestrogens (59).

Bisphosphonates

Bisphosphonates are used for the treatment of osteoporosis. They reduce bone turnover and accordingly reduce spontaneous bone fractures and bone pain (58). However, reports of osteonecrosis of the jaws have been published. The risk factors for such complication included old age, prolonged use of the drugs, dental disease, dental extraction, prolonged use of steroids and diabetic state. Accordingly, it has been advised by Goss (60) that before commencing treatment with a bisphosphonate, a patient should be dentally fit and should have regular dental checks while on treatment. 

It is evident that many alternatives to HRT are available for the treatment of osteoporosis in postmenopausal women. They have different effects on the vertebrae and femur. Alendronate, ibandronate, intranasal calcitonin, parathyroid hormones, raloxifene, risedronate, strontium ranelate and zoledronate reduce the risk of vertebral fractures. At the same time alendronate, risedronate, strontium ranelate and zoledronate reduce the risk of hip fractures as well (61). Accordingly, there is a wide choice for selecting the more suitable treatment, without the need to prescribe HRT for women over the age of 60 years, and those with higher risks of breast cancer or cardiac disease. Other important measures to reduce the risk of fractures include intake of calcium and vitamin D, as well as appropriate weight bearing exercise. It is also important that patients with osteoporosis should be careful with their life style, because of their increased liability to sustain fractures on trivial trauma.

Urogenital atrophy

A special note will be made at this point about the management of patients with urogenital atrophy. It has already been stated that the condition is under diagnosed, despite its immense negative effects on the patients’ health and sexuality. This is especially so in patients who had breast cancer, as the use of HRT is considered inappropriate or not a preferred option by the patient, because of safety issues. It may not be appreciated that almost 45% of patients on systemic HRT still suffer from urogenital symptoms (62). In both groups of patients vaginal oestrogen medication can be used to reverse the atrophic skin changes and relieve the associated symptoms. It is also effective in increasing the number of periurethral blood vessels in postmenopausal women (63). This may explain the significant improvement in urinary stress incontinence felt by patients while on similar treatment, shown by a metaanalysis conducted by Cody et al in 2009 (64). Paradoxically, the same authors reported that systemic conjugated equine oestrogen replacement therapy made incontinence worse in some patients. This was in disagreement with a randomised prospective study conducted by Long et al in 2006 (65). They found improved blood flow around the bladder neck and mid-urethra, and almost equal relief of symptoms of overactive bladder and stress incontinence following oral and transvaginal oestrogen replacement therapy, despite lower serum oestradiol levels following vaginal medication.

There is no evidence that transvaginal oestrogen replacement therapy increases the recurrence rate of breast cancer, as shown by a small study (66). Larger controlled randomized trials are necessary to confirm its absolute safety. Long term follow up studies showed no need to recommend the use of progestogens with this medication, as no evidence of endometrial proliferation could be shown even after 6-24 months of treatment (27). A distinction should be made between oestriol and conjugated equine oestrogen cream on one hand, and oestradiol tablets and low dose oestrogen rings on the other, as the first two can cause small increase in serum oestradiol (67). A metaanalysis published by Suckling et al in 2006 (68) reported significant uterine bleeding, breast pain and perineal pain following conjugate equine oestrogen use when compared to vaginal tablets in one study. It also reported significant endometrial stimulation by one study following the use of the same cream when compared to the vaginal ring. Accordingly, one should use oestradiol tablets (vagifem 25 µg, Novo Nordisk) or low-dose oestrogen rings (estring, Pfizer) for long term HRT, to guard against these side effects. Oestrogen vaginal tablets and cream are licensed for continuous use for 3-6 months in the United Kingdom, whereas low-dose vaginal ring is licensed for two years. One study showed that most women preferred using the ring over other vaginal medications because it was convenient and under their own personal control (69). The ring should be changed every 3 months. In a more recent literature review, Santos and Clissold (70) recommended the use of vaginal promestriene which is a synthetic analogue of oestradiol by patients who present with severe vulvo-vaginal symptoms and history of breast cancer. This view can be explained by previous findings by Wolff et al in 1982 (71) who documented a good local anti-atrophic effect following vaginal promestriene with no oestrogen-like systemic effects.

Endometriosis, fibroids and HRT

Two other special groups of patients need to be addressed as well; those with history of endometriosis and those with uterine fibroids. The first group is usually made of younger women who had radical surgery to remove the endometriosis, including bilateral oophorectomy. Older women with history of endometriosis who were treated medically or by conservative surgery before the menopause may also need HRT. A small undefined risk of recurrence or malignant transformation of endometriosis had been suggested, but the general consensus is that the benefits of using HRT far outweigh the risks, as suggested by Soliman and Hillard (72). This is especially so for patients who had surgery at a young age. It is generally advisable to use combined HRT with both oestrogen and progestogen, as unopposed oestrogen imposes a higher risk for recurrence. Nonetheless, there are no clinical trials to address the role of progestogens in this respect, as stated by the same authors.

The effect of HRT on fibroids is similarly not well quantified, and the risk of increase in fibroids size has been used as a factor to deny women HRT, especially those who were symptomatic before the menopause. An increase (73) and no change in the size of the fibroids (74) have been reported after using oral HRT, in doses of 0.625 conjugated equine oestrogens, with 5.0 mg or 2.5 mg medroxyprogesterone acetate (MPA) respectively. The first authors documented the change in size only during the first 2 years of medication (73). On the other hand, a randomized study showed significant increase in fibroids size after using transdermal 50 µg of ethinyl oestradiol and 5 mg MPA for one year. Tibolone (xxxx) which has oestrogenic, progestogenic and androgenic effects did not cause an increase in fibroids size in the same study (75). This fact has been confirmed by other studies (76, 77), which makes it a good option for postmenopausal women with fibroids who need HRT. Even with increased fibroids size, there are no related symptoms usually. Nonetheless, intracavitary fibroids can behave differently, and can cause abnormal uterine bleeding (78), but this was not a universal observation for all patients with similar lesions. Following a hysteroscopic study, Perrone et al (79) described intrauterine lesions in 37% and 26% of the patients who did or did not have abnormal uterine bleeding respectively while on HRT. Other benefits attributable to tibolone are that it reduced blood pressure, TNF-a and glycaemia levels in healthy postmenopausal women without any bad effect on other inflammatory factors. It did, however, reduce HDL-cholesterol levels (80). These factors should be considered when prescribing HRT.

Benign breast conditions and HRT

Women with histologically diagnosed atypia have 4-5 fold increased risk of developing breast cancer (81). The Women’s Health Initiative Study showed increased diagnosis of benign breast conditions associated with combined and unopposed HRT use (82). However, neither HRT method was shown to impose a higher risk of cancer in patients with benign breast conditions than the observed general population risk (83, 84). Current evidence shows that HRT, both combined or unopposed, does not affect the prophylactic effect of bilateral oophorectomy until the age of 50 years in premenopausal women with BRCA1 and BRCA2 mutations (85). There is no data for postmenopausal women to make affirmative conclusions. More information will be available after the publication of the Epidemiological Familial Breast Cancer, Cancer Research UK report.

Breast examinations and mammography

Women should have a full general examination before starting HRT, including weight and blood pressure. The role of repeated breast examinations is controversial, as it did not reduce breast cancer mortality in different studies. It can also result in a high number of false positive results, which may lead to unnecessary investigations and anxiety (86). Similarly, routine baseline mammography is not indicated before starting HRT, as recommended by the Royal College of Radiologists (87, 88). The situation is rather different in patients with personal history of benign breast disease with atypia, or first degree family history of premenopausal breast cancer (86). Patients between the ages of 50-65 years should be encouraged to have regular 3-yearly mammograms. Both combined and unopposed oestrogen HRT reduce the diagnostic sensitivity and specificity of mammography (89, 90). Reduced sensitivity could lead to increased interval cancer rates, delays in diagnosis, and worsens prognosis. On the other hand, reduced specificity may lead to increased positive false diagnostic rates.

Oestradiol implants and tachyphylaxis

A final note is due at this point about oestradiol implants which were very popular in the past in doses of 25, 50 and 100 mg. They were mainly used after surgical removal of the ovaries to deliver oestradiol in a controlled manner over prolonged periods of time, hence reduce the need for frequent medication. They were also used for general management of postmenopausal symptoms, at a time when other non-oral medications were not available. However, they are not as popular now and many young doctors may not even have seen any being inserted. Unfortunately, a few women using oestradiol implants develop tachyphylaxis, which indicates recurrence of postmenopausal symptoms despite high plasma oestradiol levels. This was related to the rate of fall in oestradiol blood level, rather than the absolute level itself (91). Such phenomenon was seen more often in patients who had history of psychopathology or surgical menopause (92), and had more frequent implant insertions. Prevention of tachyphylaxis should be an important objective, even before initiating this type of medication, as treatment is difficult once the problem is already established. Templeman et al in 1998 found no relationship between the recurrence of symptoms and oestradiol blood level (93). They also found that repeating implants adminstration without taking notice of oestradiol blood level resulted in continuous increase in its basal level. This should be expected as implants usually continue releasing oestradiol for much longer periods of time than the 6 monthly gaps usually used between medications. This was shown by a case report published by Wardle and Fox in 1989 (94). Oestradiol levels were 1211 pmol/l, 673 pmol/l and 169 pmol/l one year, 18 months and 3 years after the last implant insertion respectively. Counselling patients regarding the lack of agreement between symptoms score and oestradiol blood levels, and the medical risks related to high oestradiol blood levels was shown to reduce the possibility of developing tachyphylaxis (93). Patients should understand that the main biochemical objective of HRT is to restore premenopausal oestradiol blood levels with exogenous medication, and no extra oestradiol will be administered when blood levels >400 pmol/l. Such levels were maintained by 50 mg oestradiol implant insertions every 9.7 – 11.7 months as reported by Buchler et al in 1995 (95). They concluded that there was no need for more frequent prescriptions of oestradiol implants, and suggested annual adminstration instead.

There are no controlled studies regarding treatment of established cases of oestradiol tachyphylaxis. Further implant insertions should be avoided, as long as oestradiol blood level is high. The importance of thorough patients’ counselling regarding the medical risks of super physiological oestradiol blood levels has been alluded to before. Symptoms may be controlled by prescription of small doses of transdermal oestradiol, testosterone implants, or combined noradrenaline / serotonin reuptake inhibitors (Venlafaxine). The later treatment modality may be combined with a smaller implant (25 mg instead of 50 mg) in difficult cases, and progressively prolonging the period between implant insertions. Patients with psychiatric manifestations who are more prone to develop tachyphylaxis should receive psychiatric help.

Summary

Women live longer nowadays after the menopause, and expect better quality of life than their mothers and grandmothers. Accordingly, good control of the acute vasomotor symptoms, and reduction of the long term problems related to osteoporosis and CVD became a pressing medical necessity. This will also reduce the national budget necessary to cater for women who have already developed such problems. The current available options of different medications, both hormonal and non hormonal are wide enough to suit different needs. Proper selection and regular follow up on one hand, and adequate education of the patients on the other, are necessary. Family history and other risk factors of breast cancer, thrombophilia, and dyslipidaemia should be taken into consideration.

It is important to differentiate between women below and above the age of 60 years, when dealing with HRT. The effect of age in relation to breast cancer risk is well known. Furthermore, HRT is considered a promoter of pre-existing malignancy rather that an initiator of malignant transformation (96, 97), and promotes oestrogen receptor positive tumour (98). It is also associated with low grade invasive cancer at diagnosis. The review article published by Hodis and Mack in 2009 (99) explicitly addressed the risk of coronary heart disease (CHD) in relation to HRT. The main difference between the outcome of randomised controlled studies and the observational ones, mainly the WHI, was the age of the patients studied. The first group dealt with younger women, whereas the later ones dealt with older ones in relation to the menopause. Both HRT and SERMs reduced the risk of CHD in women <60 years, and in those who started treatment within 10 years of the menopause. Similarly, the current data showed no increased risk of stroke with HRT in younger (50–59 years) normotensive postmenopausal women, particularly when lower doses were prescribed soon after menopause (100). A major support for the use of HRT in young women during the menopause transition, or soon after the menopause came from the writing group on behalf of the Workshop Consensus Group of the International Menopause Society in 2009 (40). These recommendations agree with the scientific finding that oestrogens have beneficial and protective effects on the vascular endothelium. Such effect is even evident during the normal menstrual cycle in premenopausal women because of the variations in circulating oestrogen levels. Endothelial-dependent vascular dilation is greater during the later part of the follicular phase compared to the earlier part of the cycle (101). Beside its vasodilatation effect, oestrogen also has direct antioxidant and anti-inflammatory effects, both in vivo and in vitro (39).

At this point it is important to re-emphasise the need to convey risks in absolute numbers rather than percentages (42) to avoid needless alarm. This is well illustrated by the data related to breast cancer risk. The calculated risk by the age of 50-70 years for women who never used HRT is 45 cases per 1000 women. Using HRT for 5, 10 and 15 years is expected to result in 2, 6 and 12 extra breast cancers per 1000 women respectively, by the age of 70 years (102). Expressing these figures as percentages of the basal risk of 45 cases per 1000 will give alarming increased risks of 4.4%, 14.2% and 26.6% respectively.

It is high time for the regulatory authorities to change their recommendations which were made after the publication of the WHI, to match the new evidence and critical appraisal of that study and other similar ones. This view has been voiced before by many experts in the field (103, 104). HRT is safe and beneficial, when used by the right patient, and under the right supervision. Furthermore, women should be treated as individuals, and their views should be taken into consideration when they request HRT. The risk-benefit ratio should be assessed and discussed with them, before prescribing any type of medication.

References

1.    Park SJ, Goldsmith LT, Reinert A, Skurnick JH, Weiss GE. Perimenopausal women are deficient in an oestrogen positive feedback on LH secretion mechanism. 82^nd Annual Meeting of The Endocrine Society, Toronto, Canada, 21-24 June 2000: abstr 248.

2.   Matt DW, Kauma SW and Pincus SM. Characteristics of luteinising hormone secretion in younger versus older Perimenopausal women. Am J Obstet Gynecol 1998; 178: 504 - 510.

3.   Gold EB, Bromberger J, Crawford Samuels S, Greendale GA and Harlow SD. Factors associated Wellington Hospital age at natural menopause in a multiethnic sample of midlife women. Am J Epidemiol 2001; 153(9): 865 - 874.

4.   Henderson KD, Bernstein L, Henderson B, Kolonel L and Pike MC. Predictors of timing of natural menopause in multiethnic cohort study. Am J Epidemiol 22008; 167: 1287 - 1294.

5.   Do KA, Broom BM, Kuhnert P Duffy DL, Todrov AA, Treloar SA and Martin NG. Genetic analysis of the age at menopause by using estimating equations and Bayesian random effects models. Stat Med 2000; 19: 1217 - 1235.

6.   De Boer, den Tonkelaar I, te Velde ER, Burger CW, Klip H, van Leeuwen FE. Low number of retrieved oocytes at IVF treatment is predictive of early menopause. Fertil Steril 2002; 77: 978 – 985.

7.   De Boer EJ, den Tonkelaar I, te Velde ER, Burger CW, van Leeuwen FE, on behalf of the OMEGA-project group. Increased risk of early menopausal transition and natural menopause after poor response at first IVF treatment. Hum Reprod 2003; 18(7): 1544 - 1552.

8.  Genazzani AD, Stomati M, Bernardi F, Pieri M, Rovati L, and Genazzani AR. Long-term low dose dehydroepiandrosterone oral supplementation in early and late postmenopausal women modulates endocrine parameters and synthesis of neuroactive steroids. Fertil Steril 2003; 80(6): 1495 – 1501.

9.  Liu CH, Laughlin GA, Fischer µG and Yen SSC. Marked attenuation of ultradian and circadian rhythms of dehydroepiandrosterone in postmenopausal women: evidence for a reduced 17, 20-desmolase enzymatic activity. J Clin Endocrinol Metab 1990; 71(4): 900 – 906.

10. Burger H and Santoro N. Hormonal patterns in the later menopause transition. In: Textbook of Perimenopausal Gynaecology. Edit Santoro N and Goldstein SR. Parthenon Publishing Group, London, 2002: pp 13 - 17.

11. Schindler AE. Thyroid function and postmenopause. Gynecol Endocrinol 2003; 17: 79 - 85.

12. Kim DJ, Khang YH, Koh JM, Shong YK and Kim GS. Low normal TSH levels are associated with low bone mineral density in healthy postmenopausal women. Clin Endocrinol (Oxf) 2006; 64(1): 86 - 90.

13. Klein NA and Soules MR. Reproductive ageing: compensated ovarian failure. In: Textbook of Perimenopausal Gynaecology. Edit Santoro N and Goldstein SR. Parthenon Publishing Group, London, pp 5 - 12.

14. Chervenak JL. Hormonal management of symptoms. In: Textbook of Perimenopausal Gynaecology. Edit Santoro N and Goldstein SR. Parthenon Publishing Group, London, pp 145 - 158.

15. Genazzani AR, Gambacciani M, Simoncini T and Schneider HPG. Controversial issues in climacteric medicine series (3^rd Pisa Workshop on HRT in Climacteric Medicine and Ageing Brain, Pisa, Italy, March 15-18, 2003). Maturitas 2003; 46: 7 - 26.

16. Feldman BM, Voda A, Gronseth E. The prevalence of hot flushes and associated variables among postmenopaual women. Res Nurs Health 1985; 8: 261 - 268.

17. Hagstad A, Janson PO. The epidemiology of climacteric symptoms. Acta Obstet Gynecol Scand 1986; 134(suppl): 59 - 65.

18. Obermeyer CM. Menopause across cultures: a review of the evidence. Menopause 2000; 7: 184 - 192.

19. Monterrosa A, Blumel JE, Chedraui P, Gomez BA and Valdez C. Quality of life impairment among postmenopausal women varies according to race. Gynecol Endocrinol 2009; 25(8): 491 - 497

20. Greaves MW. Flushing and flushing syndromes, rosacea and perioral dermatitis. In: Champion RH, et al, eds. Rook/Wilkinson/Ebling textbook of dermatology, 6^th ed., volume 3. Oxford, UK: Blackwell Scientific, 1998: 2099 – 2104.

21. Andrikoula M, Hardiman P and Prelevic G. Menopausal hot flush: Is it only a nuisance or also a marker of cardiovascular disease risk? Gynecol Endocrinol 2009; 25(7): 450 - 454.

22. Leal M, Diaz J, Serrano E, Abellán J and Carbonell F. Hormone replacement therapy for oxidative stress in postmenopausal women with hot flushes. Obstet Gynecol 2000; 95(6 Pt 1): 804 – 809.

23. Thurston RC, Sutton-Tyrrell K, Everson-Ross SA, Hess R and Mathews KA. Hot flushes and subclinical cardiovascular disease: Findings from the study of Women’s Health Across the Nation Heart Study. Circulation 2008; 118: 1234 - 1240.

24. Rossmanith WG and Ruebberdt W. What causes hot flushes? The neuroendocrine origin of vasomotor symptoms in the menopause. Gyn Endocrinol 2009; 25(5): 303 - 314.

25. Cabanac M and Massonnet B. Thermoregulatory responses as a function of core temperature in humans. J Physiol 1977; 265: 587 - 596.

26. Freedman R and Black C. Estrogen raises the sweating threshold in postmenopausal women with hot flashes. Fertil Steril 2002; 3: 487-490.

27. Plouin PF, Duclos JM, Menard J, Comoy E, Bohuon C and Alexander JM. Biochemical tests for the diagnosis of phaeochromocytoma: urinary versus plasma concentrations. Br Med J (Clin Res Ed) 1981; 282: 853 - 854.

28.  Heron E, Chatellier G, Billaud E, Foos E and Plouin PF. The urinary metanephrines-to-creatinine ratio for the diagnosis of phaeochromocytoma. Ann Inern Med 1996; 125: 300 – 303.

29. Lenders JW, Keiser HR, Goldstein DS, Willemsen JJ, Friberg J, Jacobs MC, Kloppenborg PW, Thien T, Eisenhofer G. Plasma metanephrines in the diagnosis of phaeochromocytoma. Ann Intern Med 1996; 123: 101 – 109.

30. Al-Baghdadi O and Ewies AAA. Topical oestrogen therapy in the management of postmenopausal vaginal atrophy: an up-to-date overview. Climacteric 2009; 12: 91 - 105.

31. Stenberg A, Heimer G, Ulmsten U, Cnattingius S. Prevalence of genitourinary and other climacteric symptoms in 61 year-old women. Maturitas 1996; 24: 31 - 36. 

32. Dennerstein L, Dudley EC, Hopper JL, Guthrie JR and Burger HG. A prospective population-based study of menopausal symptoms. Obstet Gynecol 2000; 96: 351 - 358

33. Gallicchio L, Schilling C, Tomic D, Miller SR, Zacur H and Flaws JA. Correlates of sexual functioning among mid-life women. Climacteric 2007; 10: 132 - 142.

34. Verdier-Sévrain S. Effect of oestrogens on skin ageing and the potential role of selective oestrogen receptor modulators. Climacteric 200; 10: 289 - 297.

35. Creidi P, Faivre B, Agache P, Richard E, Haudiquet V and Sauvanet JP. Effect of a conjugated oestrogen (premarin) cream on ageing facial skin. A comparative study with placebo cream. Maturitas 1994; 19: 211 - 223.

36. Brincat M, Kabalan S, Studd JW, Moniz CF, de Trafford J and Montgomery JA. Study of the decrease of skin collagen content, skin thickness, and the bone mass in the postmenopausal women. Obstet Gynecol 1987; 70: 80 - 84.

37. Clermajer DS. Sorensen KE, Spiegelhalter DJ, Georgakopoulos D, Robinson J, Deanfield JE. Aging is associated with endothelial dysfuncion in healthy men years before the age-related decline in women. J Am Coll Cardiol 1994; 24: 471 – 476.

38. Mendelshon ME, Karas RH, HRT and the young at heart. N Engl J Med 2007; 2639 n= 2641.

39. Moreau KL. The modulatory influence of oestrogen on vascular endothelial function in women: Is it all about timing? Menopausal Medicine 2011; S8 – S11.

40. The Writing Group on behalf of the Workshop Consensus Group. International Menopause Society Consensus Statement. Ageing, menopause, cardiovascular disease and HRT. Climacteric 2009; 12: 368 – 377.

41.  Writing group for the women’s health initiative investigators. Risks and benefits of oestrogen plus progestin in healthy postmenopausal women: Principal results from the women's health initiative randomized controlled trial. JAMA 2002; 288: 321 - 333

42. Birkhäuser MH, Panay N, Archer DF, Barlow D, Burger h, Gambacciani M, Goldstein S, Pinkerton JA and Sturdee DW. Updated practical recommendations for hormone replacement therapy in the peri-and postmenopause. Climacteric 2008; 11: 108 - 123.

43. Rymer J, Wylie K, Barnes T, Mander A, Buckler H and Dean J. Review hypoactive sexual desire disorder. The Obstetrician and Gynaecologist 2010; 12: 237 – 243.

44. Dennerstein L, Koochaki P, Barton I, Graziottin A. Hypoactive sexual desire disorder in menopausal women: a survey of western European women. J Sex Med 2006; 3: 212 – 222.

45. Utian WH. The role of testosterone therapy in postmenopausal women: Position statement of the North American Menopause Society. Part two. Menopause Management 2006 (January / February): 18 – 32.

46. Guttoso T Jr, Kurlan K, McDermott MP, Kieburtz K. Gabapentin’s effects on hot flushes in postmenopausal women: a randomized controlled trial. Obstet Gynecol 2003; 101: 337 0 345.

47.  Aguirre W, Chedraui P, Mendoza J, Ruilova I. Gabapentin vs. low-dose transdermal oestradiol for treating postmenopausal women with moderate to very severe hot flushes. Gyn Endocrinol 2010; 26(5): 333 – 337.

48. Stomati M, Spinetti RA, Parrini D, Luisi S, Casarosa E, Petraglia F and Genzzani AR. Endocrine, neuroendocrine and behavioural effects of dehydroepiandrostenedione sulphate supplementation in postmenopausal women. Gynecol Endocrinol 1999, 13(1): 15 - 25.

49. Sahelian R, Borken S. Dehydroepiandrosterone and cardiac arrhythmia. Ann Intern Med 1998; 129(7): 588.

50. Grimley Evans J, Malouf R, Huppert F, van Niekerk JK. Dehydroepiandrosterone (DHEA) supplementation for cognitive function in healthy elderly people. Cocrane Databases Syst Rev. 2006; 4: CD006221

51. Pines A, Sturdee DW, MacLennan AH, Schneider HPG, Burger H and Fenton A. The heart of the WHI study: time for hormone therapy policies to be revised. Climacteric 2007; 10: 267 - 269.

52. Von Schoultz B. Oestrogen therapy: oral versus non-oral administration. Gyn Endocrinol 2009; 25(9): 551 - 553.

53. Birge SJ. Hormone therapy and stroke. Clin Obstet Gynecol 2008; 51: 581 - 591.

54. Canonico M, Oger E, Plu-Bureau G, Conard J, Meyer G, Levesque H, Trillot N, Barrellier MT, Wahl D, Emmerich J, Scarabin PY. Oestrogen and thromboembolic risk (ESTHER) Study Group. Hormone therapy and venous thromboembolism among postmenopausal women: impact of the route of oestrogen adminstration and progestogens: The ESTHER Study. Circulation 2007; 115: 840 – 845.

55. Clarke SC, Kelleher I, Lloyd-Jones H, Slack M, Schofiel PM. A study of hormone replacement therapy in postmenopausal women with ischaemic heart disease: the Papaworth HRT Atherosclerosis Study. BJOG 2002; 109: 1056 – 1062.

56. Lyytinen HK, Dyba T, Pukkala E, Ylikorkala O. A case controlled study on hormone therapy as a risk for breast cancer in Finland. Intrauterine system carries a risk as well. Int J Cancer 2010; 126: 483 – 489.

57. Marsden JO. Hormone replacement therapy and breast disease. The Obstetrician and Gynaecologist 2010; 12: 155 – 163.

58. Fontaine P. Endometrial cancer, cervical cancer, and the adnexal mass. Primary Care 1998; 25: 433 – 457.

59. Goldstein SR, Siddhanti S, Ciaccia AV and Plouffe L Jr. A pharmacological review of selective oestrogen receptor modulators. Hum Reprod Update 2000; 6(3): 212 - 224.

60. Goss AN. Bisphosphonate-associated osteonecrosis of the jaws. Climacteric 2007; 10: 5 - 8.

61. Rizzoli R. Osteoporosis: non-hormonal treatment. Climacteric 2007; 10(s2): 74 - 78.

62. Barlow DH, Samsioe G and van Geelen JM. A study of European women’s experience of the problems of urogenital ageing and its management. Maturitas 1997; 27: 239 - 247.

63. Kobata SA, Girão MJ, Baracat EC, Kajikawa M, Di Bella V Jr, Sartori MG, and Jármy-Di Bella ZI. Oestrogen therapy influence on periurethral vessels in postmenopausal incontinent women using Dopplervelocimetry analysis. Maturitas 2008; 20(3): 243 – 247.

64.  Cody JD, Richardson K, Moehrer B, Hextall A, and Glazener CM. Oestrogen therapy for urinary incontinence in postmenopausal women. Cochrane Database Syst Rev 2009; 7(4): CD001405.

65. Long CY, Liu CM, Hsu SC, Chen YH, Wu CH and Tsai EM. A randomized comparative study of the effects of oral and topical oestrogen therapy on the lower urinary tract of hysterectomised postmenopausal women. Fertil Steril 2006; 85(1): 155 – 160.

66. Dew JE, Wren BG and Eden JA. A cohort study of topical vaginal oestrogen therapy in women previously treated for breast cancer. Climacteric 2003; 6(1): 45 – 52.

67. Kalentzi T, and Panay N. Safety of vaginal oestrogen in postmenopaual women. The Obstetrician and Gynaecologist 2005; 7: 241 – 244.

68. Suckling J, Lethaby A, and Kennedy R. Local oestrogen for vaginal atrophy in postmenopausal women. Cochrane Database Syst Rev 2006; 18(4): CD00 1500.

69. Dezarnaulds G, and Frazer IS. Vaginal ring delivery of hormone replacement therapy – a review. Expert Opin Pharmacother 2003; 4(2): 201 – 212.

70. Santos I and Clissold S. Urogenital disorders associated with oestrogen deficiency: the role of promestriene as topical oestrogen therapy. Gynecol Endocrinol 2010; 26(9): 644 – 651.

71. Wolff JP, Cachelou R and Guẻritẻe N. Absence of systemic hormonal effects in an oestradiol diether topically active on the vaginal mucosa. Maturitas 1982; 4(4): 239 – 246.

72. Soliman NF and Hillard TC. Hormone replacement therapy in women with past history of endometriosis. Climacteric 2006; 9: 325 - 335.

73. Yang CH, Lee JN, Hsu SG, Kuo CH and Tsai EM. Effect of hormone replacement therapy on uterine fibroids in postmenopausal women- a 3-year study. Maturitas 2002; 43(1): 35 - 39.

74. Sener AB, Seckin NC, Ozmen O, Gökmen O, Doğu N and Ekici E. The effect of hormone replacement therapy on uterine fibroids in postmenopausal women. Fertil Steril 199; 5(2): 354 - 357.

75. Orsini G, Pinto V, Di Biase S, D’Altorio C and Lanzilotti G. The effects of menopausal replacement therapy in women with uterine myomas. Minerva Gynecol 1999; 51(11): 421 - 425.

76. Fedele L, Bianchi SS, Raffaelli R ad Zanconato G. A randomized study of the effects of tibolone and transdermal oestrogen replacement therapy in postmenopausal women with uterine myomas. Eur J Obstet Gynecol Reprod Biol 2000; 88(1): 91 - 94.

77. Gregoriou O, Konidaris S, Botsis D, Papadias C, Makrakis E and Creatsas G. Long term effects of tibolone on postmenopausal women with uterine myomas. Maturitas 2001; 401(1): 95 - 99.

78. Akkad AA. Habiba MA, Ismail N, Abrams K and al-Azzawi F. Abnormal uterine bleeding on hormone replacement: the importance of intrauterine structural abnormalities. Obstet Gynecol 1995; 86(3): 330 - 334.

79. Perrone G, DeAngelis C, Critelli C, Capri O, Galoppi P, Santoro G, Nofroni I and Zichella L. Hysteroscopic findings in postmenopausal abnormal uterine bleeding: a comparison between HRT users and non-users. Maturitas 2002; 43: 251 - 255.

80. Santen RJ, Mansel R. Benign breast disorders. N Engl J Med 2005; 353: 275 - 285

81.  Rohan TE, Negassa A, Chlebowski RT, Hable L, McTiieman A, Ginsberg M, Wassertheil-Smoller S, Page DL. Conjugated equine oestrogen and risk of benign proliferative breast disease: a randomised controlled trial. J Natl Cancer Inst 2008; 100: 563 – 571.

82.  Anderson GL, Limacher M, Assaf AR, Bassford T, Beresford SA, Black H, Bonds D, Brunner R, Brzysk R, Caan B, Chlebowski R, Curb D, Gass M, Hays J, Heiss G, Hendrix S, Howard BV, Hsia J, Hubbell A, Jackson A, Johnson R, Johnson KC, Judd H, Kotchen JM et al. Women’s Health Initiative Steering Committee. Effects of conjugated equine oestrogen in postmenopausal women with hysterectomy: the Women’s Health Initiative randomized controlled trial. JAMA 2004; 291: 1701 – 1712.

83. Stefanick ML, Anderson GL, Margolis KL, Hendrix SL, Rodabough RL, Paskett ED, Lane DS, Hubbell FA, Assaf AR, Sarto GE, Schenken RS, Yasmeen S, Lessin L, Chlebowski RT. WHI Investigators. Effect of conjugated equine oestrogen on breast cancer and mammography screening in postmenopausal women with hysterectomy. JAMA 2006; 295: 1647 – 1657.

84. Domchek SM, Rebbeck TR. Prophylactic oophorectomy in women at increased cancer risk. Curr Opin Obstet Gynecol 2007; 19: 27 – 30.

85. Page C, and Glasier A. (2000). Monitoring of women on hormone replacement therapy: what should we be doing? In: John Studd (ed.). The Management of the Menopause. The Millennium Review. (49 – 57). Carnforth, Lancashire: Parthenon Publishing Limited.

86.  Royal College of Radiologists. Hormone replacement therapy mammography. Reference List for Royal College of Radiologists Guidelines 1993: FCR/5/93.

87. Royal College of Radiologists Working Party. Making the best use of clinical radiology: Guidelines for doctors, 4^th edn; London: RCR, 1998.

88. Banks E. Hormone replacement therapy and the sensitivity and specificity of breast screening: a review. J Med Screen 2001; 8: 29 – 34.

89. Banks E, Reeves G, Beral V, Bull D, Crossley B, Simmonds M, Hilton E, Bailey S, Barrett N,  Briers P, English R, Jackson A, Kutt E, Lavelle J, Rockall L, Wallis MG, Wilson M, Patrick J. Hormone replacement therapy and false positive recall in the million women study: pattern of use, hormonal constituents and consistency of effect. Breast Cancer Res 2006; 8: R8. Doi:10. 1186/bcr1364.

90. Vassalle C, Cicinelli E, Lello S, Mercuri A, Battaglia D, Maffei S. Effects of menopause and tibolone on different cardiovascular biomarkers in healthy women. Gyn Endocrinol 2011, 27(3): 163 – 169.

91. Alder EM, Bancroft J and Livingstone J. Oestradiol implants, hormone levels and reported symptoms. J Psychosom Obst Gyn 1922; 13(3): 223 – 235.

92. Garnett T, Studd JW, Henderson A, Watson N, Savvas M, and Leather A. Hormone implants and tachyphylaxis. Br J Obstet Gynaecol 1990; 97(10): 917 -921.

93. Templeman C, Quinn D, Hansen R, Moreton T and Baber R. An audit of oestrogen implant hormone replacement therapy. Aust N Z J Obstet Gynaecol 1998; 38(4): 455 – 460.

94. Wardle P and Fox R. Symptoms of oestrogen deficiency in women with oestradiol implants. BMJ 1989; 299: 1102.

95. Buchler HM, Kaisi PK, Cantrill A, and Andersen DC. An audit of oestradiol levels in women undergoing subcutaneous implant therapy. Clin Endocrinol (Oxf.) 1995; 42(5): 445 – 450.

96. The Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and HRT: collaborative reanalysis of data from 51 epidemiological studies of 52705 women with breast cancer and 108411women without breast cancer. Lancet 1997; 350: 1047 – 1059.

97.  Eden JA. Why does oestrogen-only hormone therapy have such a small impact on breast cancer? Gyn Endocrinol; 27(3): 170 – 175.

98.  Du XL, Fox EE, Lai D. Competing causes of death for women with breast cancer and change overtime from 1975 to 2003. Am J Oncol 2008; 31: 105 – 118.

99.  Hodis HN and Mack WJ. Coronary disease and hormone replacement therapy after the menopause. Climacteric 2009; 12(s1): 71 - 75.

100.  Lobo RA. Menopause and stroke and the effects of hormonal therapy. Climacteric 2007; 10(s 2): 27 – 31.

101.  Hashimoto M, Akishita M, Eto M, Ishikawa M, Kozaki K, Toba K, Sagara Y, Taketani Y, Orimo H, Ouchi Y. Modulation of endothelium-dependent flow-mediated dilatation of the brachial artery by sex and menstrual cycle. Circulation 1995; 92: 3431 – 3435.

102.   Wise J. Hormone replacement therapy increases the risk of breast cancer. BMJ 1997; 315: 969.

103.  Gambacciani, M. Ciaponi and A. R. Genazzani. The HRT misuse and osteoporosis epidemic: a possible future scenario. Climacteric 2007; 10: 273 – 275.

104.  Lumsden MA. The position of the Regulatory Authorities. Climacteric 2007; 10(s2): 121 – 124.