What Is Menopause?
Source: Copyright © 2008 Harvard Health Publications | Date Posted: May 1, 2008
In-Depth Report
What is menopause?
Medical experts determine that a woman has reached menopause if she hasn't had a period for 12 consecutive months and there's no underlying medical condition causing her to stop menstruating. On average, women in Western nations can expect to have their last menstrual period at about age 51. In women who smoke, menstruation may stop a year or two earlier. But it varies widely. Some women have their last period when they're still in their 40s; others not until they are 60. Premature menopause, defined as menopause that takes place before age 40, may result from chemotherapy, radiation treatment, or premature ovarian failure, that is, early ovarian dysfunction. This sometimes runs in families and sometimes is an autoimmune disease. Surgical menopause — when the ovaries are surgically removed, often done at the time of hysterectomy — can happen at any age.
The biology of menopause
When you are born, your ovaries hold one million to two million egg-containing follicles. But over time, the number declines steadily as you ovulate or the follicles simply disintegrate. When the follicle supply is depleted, your ovaries stop making estrogen and progesterone, the hormones that have regulated your periods through the years. During the time preceding menopause, ovulation and estrogen production become erratic, causing periods to become irregular.
You might think of estrogen as a female hormone because of its important role in menstruation and reproduction. However, its effects are by no means limited to the reproductive system. Estrogen receptors — proteins that estrogen molecules link up with to exert its effects — are found in cells of the liver, digestive system, urinary tract, blood vessels, bones, skin, and brain, among others. When estrogen links to these receptors, it stimulates the cells to produce proteins that help maintain the healthy functions of these tissues and organs. In this way, estrogen has a role in determining the composition of lipids in the blood, the density of bones, the regulation of body temperature, the ability to recall information from memory, and the elasticity of skin and arteries.
Follicle-stimulating hormone (FSH) is the brain hormone that triggers estrogen production in the ovaries during the childbearing years. When estrogen levels drop, FSH rises, trying to stimulate your ovaries to produce more estrogen and maintain your menstrual cycle. High FSH levels may indicate that the menopausal transition has begun.
Eventually, your periods stop for good. The postmenopausal years begin a year after your last period, and last for the rest of your life. This time of life is more than just a postscript to the cessation of menstruation. This is an opportunity for women to pay close attention to the development of such chronic illnesses as osteoporosis, heart disease, and cancer. If you haven't already taken up healthy habits — exercising, eating well, avoiding smoking, and reducing stress — doing so now can help ensure good health during the postmenopausal years.
Monthly hormone cycle
During a woman's reproductive years, her hormones follow a regular monthly pattern of ups and downs. Follicle-stimulating hormone (FSH) stimulates the growth of a fluid-filled follicle containing an egg. Luteinizing hormone (LH) tells the ovary to produce more estrogen to spur the release of an egg. After the egg erupts from the follicle (ovulation), the follicle remnant, known as the corpus luteum, produces progesterone, which stimulates the growth of the endometrium (lining of the uterus) to receive and nourish a fertilized egg. Meanwhile, FSH and LH levels drop and, if no fertilized egg reaches the endometrium, the cycle repeats itself the next month unless of course a woman conceives. |
Perimenopause
Estrogen doesn't disappear suddenly. Even though women don't reach menopause until an average age of 51, the effects of declining estrogen may be noticeable as early as age 35 in the form of decreased fertility and irregular periods. This time of early symptoms — caused by hormonal changes related to aging ovaries — is known as perimenopause.
Perimenopause varies greatly from one woman to the next. It may last only a few months or several years. Symptoms may be mild or severe. Only a small percentage of women have no symptoms at all. The earliest sign of perimenopause may be declining fertility; for someone planning a pregnancy, this can be a major issue. Even for those who aren't planning a pregnancy, early symptoms of menopause such as fluctuating periods or shorter menstrual cycles or hot flashes well before age 50 can be bewildering.
The ups and downs of perimenopause
If you've ever wondered why a woman's period becomes irregular or unpredictable during perimenopause, examine this graph, which charts six months of hormone levels for a perimenopausal woman. Instead of a repetitive monthly pattern, hormone levels fluctuate unpredictably, producing an early period one month, an unusually heavy period the next, and perhaps none at all the following month. |
How do you know whether irregular periods, hot flashes, or insomnia are caused by perimenopause or a medical condition? There is no reliable test to tell if you're in perimenopause. Your doctor could measure your FSH level to see if it is elevated. You can also buy a kit at the drugstore to check your FSH level. But during perimenopause, estrogen levels rise and fall erratically, and so do FSH levels. Results from an FSH test may vary from day to day, so a single test won't provide you with a clear picture of what is happening. But a mildly elevated FSH level on the third day of your menstrual period appears to correlate with diminished fertility — a harbinger of menopause.
Even though there is no clear-cut test for perimenopause, you will probably notice when changes begin in your body. Is your menstrual cycle noticeably different in a consistent pattern from a few years ago? Is your cycle shorter or your flow heavier? Insomnia may also coincide with the hormonal fluctuations of perimenopause, especially right before your period. Among women this age, other symptoms such as irritability and memory loss are common, although their relationship to menopause is not certain. The first appearance of some of these symptoms can be alarming for women who aren't aware that perimenopause can begin years in advance of menopause. Recognizing these changes as a normal part of aging will help you and your clinician manage them effectively and plan for a healthy future.
Premature menopause
The loss of ovarian function before age 40 is called premature menopause. It resembles natural menopause in many ways, including low estrogen levels and loss of fertility. Symptoms such as hot flashes are likely to appear. Additional emotional stress often accompanies premature menopause, as women cope with making this transition earlier in life than their contemporaries. Women and their clinicians sometimes fail to recognize premature menopause because they don't consider menopause a possibility in younger women.
There are several known causes of premature menopause. In some cases it runs in some families and may have a genetic basis. Autoimmune damage to the ovaries can also cause ovarian failure. Some medical treatments cause early menopause, including removal of the ovaries (oophorectomy), often done along with hysterectomy (removal of the uterus). If you need a hysterectomy, you may be able to have only your uterus removed, leaving your ovaries in place to maintain better hormone levels. Removal of the uterus alone may accelerate menopause, but it does not cause the sudden transition that results from removing the ovaries.
Temporary or even permanent menopause can occur in premenopausal women who undergo cancer chemotherapy or pelvic radiation treatments. Drug treatment with GnRH antagonists, which are sometimes used for fibroids, endometriosis, or severe premenstrual syndrome (PMS), also causes temporary menopause. Once this treatment stops, the ovaries usually resume their normal hormonal functioning.
Women who experience permanent premature menopause — whether from a genetic predisposition, autoimmune disease, surgery, or treatments toxic to the ovary — may be at somewhat greater risk for some later-life conditions such as osteoporosis and heart disease. They are also likely to experience worse-than-average menopausal symptoms. These women should talk with their doctors about measures to manage their particular situation.
|
The rise and fall of hormone therapy Recent decades have been a roller coaster ride for women on menopausal hormone therapy, or HT — long called hormone replacement therapy, or HRT. The number of women taking estrogen at menopause rose during the 1960s, when this treatment was touted by some experts as a virtual cure-all for women's midlife woes. Premarin, the oldest prescription hormone replacement drug, is a mixture of estrogens derived from the urine of pregnant mares (hence the name, Pre-mar-in). Taken in pill form, the drug was prescribed to replace women's "missing" estrogen and relieve menopausal complaints. Estrogen was later found to help combat osteoporosis, a common, disabling bone disease among elderly women. Subsequent research suggested that estrogen therapy might also lower the risk of heart disease, the nation's leading cause of death in postmenopausal women. By the early 1990s, Premarin was the most widely prescribed drug in the United States. Millions of women who had not undergone hysterectomy were also taking progestogens to counteract the increased risk of uterine cancer discovered among estrogen users in the 1970s. Although the annoying symptoms of menopause typically fade after a few years, many women stayed on hormones for far longer, sometimes for decades. Many doctors encouraged women to keep refilling their prescriptions, since the prevailing wisdom was that long-term HRT helped fend off osteoporosis and heart disease. But by the late 1990s, evidence from several studies had cast doubt on the heart-protecting benefits of hormones. And in 2002, after new evidence from a major, long-term research study demonstrated that Prempro (a combination of estrogen and progestogen) slightly increased the risk of heart disease, stroke, serious blood clots, and breast cancer, a revolution ensued. Throughout the nation, an estimated 6 million women who were then taking hormones were urged to discuss the situation with their clinicians. Many doctors advised their patients to stop taking the drugs, and hormone prescriptions dropped dramatically. Hormone therapy, as it's now called, is no longer routine treatment for menopausal women. |
Review Date: 2008-05-01
Harvard Medical School does not endorse products or services.
Share
preview