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Menopause
The word menopause literally means the permanent physiological, or natural, cessation of menstrual cycles, from the Greek roots 'meno-' (month) and 'pausis' (a pause, a cessation). In other words, menopause means the natural and permanent stopping of the monthly female reproductive cycles, and in humans this is usually indicated by a permanent absence of monthly periods or menstruation.
The word is commonly used in regard to human females, where menopause happens more or less in midlife, signaling the end of the fertile phase of a woman's life. Menopause is perhaps most easily understood as the opposite process to menarche.
Menopause in women cannot however simply be defined as the permanent "stopping of the monthly periods", because in reality what is happening to the uterus is quite secondary to the process. For medical reasons, the uterus is sometimes surgically removed (hysterectomy) in a younger woman, and after this her periods will cease permanently and the woman will technically be infertile, but as long as her ovaries (or one ovary) are, or is, still functioning, the woman will not be in menopause. This is because, even without the uterus, ovulation, and the release of the sequence of reproductive hormones that are an essential part of the reproductive cycles, will continue until the time of menopause is reached.
Menopause is in fact triggered by the faltering and shutting down (or surgical removal) of the ovaries, which are a part of the body's endocrine system of hormone production, in this case the hormones which make reproduction possible and influence sexual behavior.
The process of the ovaries shutting down is a phenomenon which involves the entire cascade of a woman's reproductive functioning from brain to skin, and this major physiological event usually has some effect on almost every aspect of a woman's body and life.
Overview
Menopause starts as the ovaries begin to fail to be able to produce an egg or ovum every month. Since the process of producing and ripening the egg is also what creates several of the key hormones involved in the monthly cycle, this in turn interrupts the regular pattern of the hormone cycles, and gradually leads to the somewhat chaotic and long-drawn out shutting down of the whole reproductive system.
The break-up in the pattern of the menstrual cycles not only causes the levels of most of the reproductive hormones to drop over time, but also causes the reproductive hormones to fall out of phase with one another, which often leads to extreme and unpredictable fluctuations in the levels, which itself can cause numerous different symptoms such as hot flashes, etc, in most women. After a number of years of erratic functioning, the ovaries almost completely stop producing hormones including the estrogens, progestin and testosterone, and the reproductive system ceases to function.
Age of onset
The average age of menopause is 51 years, and the normal age range for last period ever is somewhere between age 45 to 55. Age 55 to 60 for last period ever is described as a "late menopause". An "early menopause" is defined as last period ever between the age of 40 to 45.
Some women reach menopause at a much younger age than average, especially if they have had cancer or another serious illness, and have undergone chemotherapy. This is sometimes referred to as a "chemical menopause".
Premature menopause (or premature ovarian failure) is defined as last period ever occurring before the age of 40; it occurs in 1% of women and is not viewed as being due to normal causes. Some known causes of spontaneous premature menopause include autoimmune disorders, thyroid disease, and diabetes mellitus, but often it is idiopathic in nature.
Premature menopause is diagnosed or confirmed by measuring the levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH); the levels of these hormones will be higher if menopause has occurred. Rates of premature menopause have been found to be significantly higher in fraternal and identical twins; approximately 5% of twins reach menopause before the age of 40. The reasons for this are not completely understood. Transplants of ovarian tissue between identical twins have been successful in restoring fertility.
Menopause in other species
Menopause in the animal kingdom appears perhaps to be somewhat rare, although this has not been thoroughly researched. However, it is already quite apparent that humans are not the only species that experience it.
Menopause has been observed in rhesus monkeys, some cetaceans, as well as in a variety of other species of vertebrates including the guppy, the platyfish, budgerigars or “parakeets”, laboratory rats and mice, the opossum, and all manner of primates.
The possible significance of menopause in human evolution
The Grandmother hypothesis considers that the menopause may have been selected for in human evolution, because later life infertility could actually have conferred an evolutionary advantage by allowing older women to spend more time helping with the survival of their existing children and grandchildren.
Terminology, definitions and commentary
Menopause
Clinically speaking, menopause is a date: for those women who still have a uterus, menopause is defined as the day after a woman's last period ever finishes.
In common everyday parlance however, the word "menopause" is usually not used to refer to one day, but to the whole of the menopause transition years. This span of time is also referred to as the change of life or the climacteric and more recently is known as "perimenopause", (literally meaning "around menopause").
Perimenopause
Perimenopause means the menopause transition years, the years both before and after the last period ever, when the majority of women find that they undergo at least some symptoms of hormonal change and fluctuation, such as hot flashes, mood changes, insomnia, fatigue, memory problems, etc.
During perimenopause, the production of most of the reproductive hormones, including the estrogens, progesterone and testosterone, diminishes and becomes more irregular, often with wide and unpredictable fluctuations in levels. During this period, fertility diminishes.
Symptoms of perimenopause can begin as early as age 35, although most women become aware of them about 10 years later than this. Perimenopause can last for a few years, or for ten years or even longer. In this respect it resembles puberty, a similar process that surrounds menarche. In fact menopause can usefully be compared to "puberty in reverse", and the psychological challenges and adjustments which take place over this time span can be compared to adolescence.
The actual duration and severity of perimenopause in any individual woman cannot be predicted in advance or during the process. Not every woman experiences symptoms during perimenopause. Approximately one third of all women get no noticeable symptoms other than their periods becoming erratic and then stopping. Another one third of women have moderate symptoms. The remaining one third of women have very strong symptoms which tend to have a longer duration. The tendency to have a very strong perimenopause may be inherited in some cases.
One piece of recent research appears to show that melatonin supplementation in perimenopausal women can produce a highly significant improvement in thyroid function and gonadotropin levels, as well as restoring fertility and menstruation and preventing the depression associated with the menopause.
Premenopause
Premenopause is a word used to describe the years leading up to the last period ever, when the levels of reproductive hormones are already becoming lower and more erratic, and symptoms of hormone withdrawal may be present.
Postmenopause
Postmenopause is all of the time in a woman's life that take place after her last period ever, or more accurately, all of the time that follows the point when her ovaries become inactive.
A woman who still has her uterus can be declared to be in post-menopause once she has gone 12 full months with no flow at all, not even any spotting. When she reaches that point, she is one year into post-menopause. The reason for this delay in declaring a woman post-menopausal is because periods become very erratic at this time of life, and therefore a reasonably long stretch of time is necessary to be sure that the cycling has actually ceased.
In women who have no uterus, and therefore have no periods, post-menopause can be determined by a blood test which can reveal the very high levels of Follicle Stimulating Hormone (FSH) that are typical of post-menopausal women.
A woman's reproductive hormone levels continue to drop and fluctuate for some time into post-menopause, so any hormone withdrawal symptoms that a woman may be experiencing do not necessarily stop right away, but may take quite some time, even several years, to disappear completely.
Any period-like flow that might occur during post-menopause, even just spotting, must be reported to a doctor. The cause may be minor, but the possibility of endometrial cancer must be checked for and eliminated.
The causes of menopause
A natural or physiological menopause is that which occurs as a part of a woman's normal aging process. It is the result of the eventual atresia of almost all oocytes in the ovaries. This causes an increase in circulating follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels as there are a decreased number of oocytes responding to these hormones and producing estrogen. This decrease in the production of estrogen leads to the perimenopausal symptoms of hot flashes, insomnia and mood changes, as well as post-menopausal osteoporosis and vaginal atrophy.
However, menopause can be surgically induced by bilateral salpingo-oophorectomy (removal of both ovaries and both fallopian tubes), which is often, but not always, done in conjunction with hysterectomy. Cessation of menses as a result of removal of the ovaries is called "surgical menopause". The sudden and complete drop in reproductive hormone levels usually produces extreme hormone-withdrawal symptoms such as hot flashes, etc.
As mentioned above, removal of the uterus, hysterectomy, does not itself cause menopause, although pelvic surgery can sometimes precipitate a somewhat earlier menopause, perhaps because of a compromised blood supply to the ovaries. Removing the ovaries however, causes an immediate and powerful "surgical menopause", even if the uterus is left intact.
Cigarette smoking has been found to decrease the age at menopause by as much as one year, and women who have undergone hysterectomy with ovary conservation go through menopause 3.7 years earlier than average. However, premature menopause (before the age of 40) is generally idiopathic.
Symptoms of perimenopause, the menopause transition time
As the body struggles to adapt to the rapidly changing levels of natural hormones, vasomotor symptoms such as hot flashes and palpitations, psychological symptoms such as depression, anxiety, irritability, mood swings and lack of concentration, and atrophic symptoms such as vaginal dryness and urgency of urination appear. Together with these symptoms, the average woman also has increasingly erratic menstrual periods.
These perimenopause symptoms are caused by an overall drop, as well as dramatic but erratic fluctuations, in the levels of estrogens, progestin, and testosterone. Some of these symptoms such as formication, may be associated directly with hormone withdrawal.
Vasomotor instability
- hot flashes or hot flushes, including night sweats
- sleep disturbances
Urogenital atrophy
- itching
- dryness
- bleeding
- watery discharge
- urinary frequency
- urinary urgency
- urinary incontinence
Skeletal
- osteoporosis gradually developing over time
- joint pain, muscle pain
- back pain
Skin, soft tissue
- breast atrophy
- skin thinning
- decreased elasticity
- formication, a sensation of pins and needles, or ants crawling on or under the skin
Psychological
- mood disturbance
- irritability
- fatigue
- memory loss and problems with concentration
- depression
Sexual
- decreased libido
- vaginal dryness
- problems reaching orgasm
- dyspareunia
One cohort study found that menopause was associated with hot flashes; joint pain and muscle pain; and depressed mood. In the same study, it appeared that menopause was not associated with poor sleep, decreased libido, and vaginal dryness.
Text and images are licensed under the GNU Free Documentation License. Material is used from the Wikipedia article "Menopause".
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