The Role of Hormones in Your Health

Nearly every preceding chapter of this book offers some information about hormones — their role in your body and the impact of changing hormone levels on your health. But as you move into the decision about hormone therapy, it's important that you remember a few of the more important facts about hormones. For example, though your body produces a number of hormones, three hormones play leading roles in your reproductive cycle: estrogen, progesterone, and androgens. All three of these hormones can be used in hormone therapy and therefore may continue to play a role in your health from puberty through your mature years.

Because hormones are such an important and widely used tool for controlling menopausal symptoms, including hot flashes, night sweats, mood swings, vaginal atrophy, and later, bone loss and deteriorating vision, they are the subject of constant, ongoing medical research.

The Women's Health Initiative (WHI) Study

In 1991 the National Institutes of Health began a fifteen-year study of over 150,000 women, age fifty to seventy-nine, that was designed to examine a number of factors as they relate to the prevention of heart disease, cancer, and osteoporosis. One subsection of this enormous study was a clinical trial study involving 68,000 postmenopausal women. These women could participate in any or all three of three preventive approaches: hormone therapy, dietary modifications, and/or calcium and vitamin D supplementation.


There are many terms to refer to hormone therapy. “HRT” refers to Hormone Replacement Therapy. A variation of that, “ERT” stands for Estrogen Replacement Therapy. Since some scientists maintain that they are not “replacing” but rather “creating” a hormonal environment, the terms “MHT,” for menopausal hormone therapy, and “HT,” for hormone therapy are becoming more common. “ET” usually refers to Estrogen Therapy, without other hormones, and “EPT” to Estrogen combined with Progestin Therapy.

The hormone therapy study was randomly divided between placebo groups and estrogen, or estrogen and progestin, therapies. Women taking either placebo or hormone regimens were studied to determine their risk for cardiovascular disease and cancer. During the first five years of the study, the percentage of woman between the ages of fifty and seventy-four using MHT went from 33 percent to 42 percent. It was conventional wisdom at that time that using estrogen would delay heart disease, osteoporosis, and aging in general.

In 2002, study findings were beginning to show that not only was hormone therapy not protective against heart disease and stroke, but that women on hormones actually had an increased risk of those conditions. The study was stopped, and women were advised not to go on hormone therapy to prevent heart disease and/or stroke. Women and their physicians were left confused and wondering how to deal with this information. Thousands of women were taken off estrogen and other hormone combinations, and prescriptions for hormone therapy dropped 38 percent in the first year following publication of the results. Since then, scientists have analyzed the data to determine more clearly what the risks are and in what cases hormone therapy may be advisable for women. Recent evidence suggests that women are returning slowly to use of MHT, but for shorter periods of time, and at lower doses. These benefits and risks will be described later, but for the latest developments and findings from the WHI study, go to

Estrogen and Its Use in MHT

Estrogen is a growth hormone that stimulates the development of adult sex organs during puberty. Estrogen helps retain calcium in bones, a function that keeps bones strong and whole during childbearing years. It also regulates the balance of cholesterol in the bloodstream and helps lower your body's total cholesterol level (see Menopause and Heart Disease in Chapter 14). Estrogen aids other body functions, such as regulating blood sugar levels and emotional balance. It helps keep skin supple and elastic through its nonstop job of replacing dead cells and maintaining proper collagen structure (the basic structural component of skin and supporting structures). Similarly, it promotes healthy, well-nourished vaginal tissue to help maintain flexible, moist, and elastic vaginal walls.


If you have your uterus, your health care professional won't prescribe unopposed estrogen for treatment of menopausal symptoms. Be aware, however, that if you self-medicate with plant estrogens (phytoestrogens) from soy foods or supplements, you may be giving your body unopposed estrogens. Talk to your health care provider about any and all supplements and vitamins you take on a regular basis.

The amount of hormones your ovaries are able to secrete gradually diminishes in your late forties, so your body produces lower amounts of estrogen and other hormones. In the early stages of perimenopause, the pituitary gland in the brain produces its own hormones to try to stimulate the ovaries to produce more estrogen, and it works, for a while. The ovaries occasionally are able to develop an egg that produces enough estrogen to trigger a menstrual period. However, in this transition phase a woman may experience widely fluctuating levels of estrogen for a number of years, until the ovaries shut down completely. The body continues to produce small amounts of estrogen, but only at about 25 percent or less of its premenopause rate — levels too small to support the hormone's age-defying functions in the body.

Estrogen is used in MHT to:

  • Diminish hot flashes

  • Keep the vaginal walls supple, moist, and well nourished

  • Maintain or even increase bone density

  • Help alleviate urinary tract problems and diminish stress and urge incontinence

  • Lower the risk of age-related macular degeneration of the eye and glaucoma (when used with progestin)

  • Lower the risk of rheumatoid arthritis and improve the motor symptoms of Parkinson's disease

Estrogen's powerful benefits have resulted in its use for perimenopausal symptoms for more than fifty years. In the 1950s and 1960s, many doctors prescribed unopposed estrogen replacement — meaning that the woman received estrogen alone — without the balancing effects of the hormone progesterone, even if she had an intact uterus. But later studies revealed that estrogen given alone could result in the development of endometrial cancer, so MHT today almost always involves some combination of estrogen, progesterone, and in some cases, androgens such as testosterone. If a woman has had a hysterectomy, she doesn't need to worry about endometrial cancer, so her hormone prescription may be estrogen alone, known as ET, estrogen therapy.

Estrogen Therapy

Estrogens offer many health benefits, but these powerful hormones can have some negative effects. Estrogen can contribute to the occurrence of blood clots in the deep veins of the legs or the lungs of women who have a history of these problems.


It was thought that estrogen might prevent the onset of Alzheimer's disease or other types of dementia, but the Women's Health Initiative (WHI) study did not show that at all. In fact, there was some indication that women taking estrogen might develop these conditions sooner. As with other findings in this study, the results will be refined to determine which women are at greatest risk. In the meantime, MHT is not recommended for prevention of dementia and memory loss.

As you progress through perimenopause, your body's hormonal changes take place over a period of months or years, giving your system time to adjust to gradually declining hormone levels. If you go through an induced menopause — for example, following the surgical removal of the ovaries — your menopause will be immediate and probably dramatic in its physical impact. In those cases, your doctor or health care provider is likely to recommend some form of estrogen therapy to help your body through the transition.

Progesterone and Its Use in MHT

Progesterone is an important hormone, though its benefits and impact may seem less dramatic than those of estrogen. Normally, your ovaries produce progesterone in the process of ovulation, so most women in their reproductive years that report having regular menstrual cycles would be expected to have normal progesterone levels. Progesterone stabilizes the growth of your uterine lining (endometrium) thereby limiting the quantity of your menstrual blood flow. In your childbearing years, progesterone also promotes the development of nutrients in the uterus, breasts, and fallopian tubes to prepare your body for supporting a pregnancy.


One of the promising results from the WHI study was the impact of MHT on hip fractures and colorectal cancers. Both were reduced in women taking hormone therapy, so if you are at increased risk of osteoporosis or have a strong family history of colorectal cancer, discuss this with your health care provider when deciding whether MHT is for you.

Your progesterone levels drop dramatically when you stop ovulating. Because progesterone's most important effect in your body is its estrogen-balancing capabilities, most MHT prescriptions for women who still have a uterus include some type of progestin, a pharmaceutical form of the naturally occurring hormone progesterone.

In spite of its critical importance for balancing the effects of estrogen, progestin has its drawbacks. Some women experience breast tenderness and water retention when taking progestin with estrogen in an MHT regimen. Other women find that some forms of progestin aggravate mood swings. And many forms of progestin can diminish the heart-healthy effects of estrogen, which is why doctors usually don't include progestin therapy in MHT if a woman has had a hysterectomy.

For these reasons, doctors and health care providers monitor hormone therapy patients carefully to determine which progestin type and delivery technique works best for each individual. If you have a medical history of high cholesterol, discuss this history with your doctor before deciding on an MHT prescription.

A number of different types of progestins are available, and it can be taken continuously, cyclically (twelve to fourteen days of every month), or in a pulsed regimen of three days on and three days off. Progestins given in a cyclic fashion usually produce a predictable menstrual period; progestins given in the same dose on a daily basis are designed to make most women period-free after one year of therapy or sooner.

Androgens in MHT

Androgens are male hormones that are normally produced in small quantities by the ovaries and adrenal glands, with the greatest quantities occurring at the midpoint of a woman's cycle. Androgens contribute to bone density (though not as dramatically as do estrogens), and some studies show that they might promote a healthy libido by fostering a desire for sex. Androgen production also drops dramatically when ovarian function decreases around the time of perimenopause. The decrease is even more dramatic if a woman undergoes a surgical menopause. If women have severe menopausal or perimenopausal symptoms, such as intermittent hot flashes or a greatly reduced sex drive, despite a trial of traditional MHT, their health care providers may recommend an MHT regimen that includes androgens.

The use of androgens to combat menopausal symptoms is relatively new, unlike estrogen, which has been used and studied since the mid-1950s. Some studies have shown that androgen in combination with estrogen not only slows bone loss but also may help promote the growth of new bone tissue. Some experts believe androgens help alleviate other menopausal symptoms such as hot flashes and vaginal dryness. Androgens carry some risks, of course; some studies suggest that androgen can have a negative effect on blood cholesterol levels, and a few patients who take androgens can experience unwanted side effects such as the growth of excess body hair (especially on the face), acne, or oiliness of the skin. In general, androgens are added to an MHT regimen only if libido or hot flashes are not improved on standard MHT dosages.


More than half of the women who experience irregular spotting or bleeding after beginning an MHT regimen that includes progestin stop bleeding completely after six months; 80 percent stop bleeding within a year. Continued bleeding (after one year) may indicate a problem with the lining of the uterus, rather than a reaction to MHT.

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