Let’s discuss several hormonal scenarios: (1) You’ve been on hormones for several years and now think you may try to stop. (2) You have just started having hot flashes and you haven’t quite made up your mind as to whether you will want to take hormones during the menopausal transition. (3) You are not yet menopausal but worry about what you will experience when it inevitably develops.

The defining question for most women (at least in regards to quality of daily life) is: “How long will I experience hot flashes?” One would think that since menopause has been around before and since the written word that we could estimate the average duration of this pesky and sweaty symptom. (Well maybe not, 120 years ago the average life expectancy for women was 47 and most did not outlive their ovaries.)

Hot flashes generally begin when estrogen levels plummet in menopausal or during the premenopausal transitions. The ovaries run out of follicles that are capable of responding to pituitary messages to develop and hence produce estrogen. In the absence of said estrogen, the pituitary works harder (it’s trying to get those damn follicles to work), hence it puts out more and more FSH (follicle stimulating hormone). The pituitary gets its signals from the part of the brain called the hypothalamus which produces GnRH or gonadotropic releasing hormone, the master hormone that instigates FSH production. In the absence of “usual” estrogen production, GnRH and FSH levels soar and there is a veritable hypothalamic storm. This then causes a state of confusion in the central thermostat in the brain which begins to “think” that the body’s core temperature is too hot. In order to correct this, the hypothalamus sends out directives to dilate the small blood vessels in the skin (the flush) and causes water to evaporate from the skin’s surface (as sweat, facial and body perspiration) in order to cool the body down. All of this may lower the core body temperature by as much as half a degree. Often subsequent to a hot flash, a woman may shiver as small muscles contract to re-elevate the core body temperature.

Hot flashes are associated with poor sleep, decreased quality of life, may worsen depressive symptoms and even signal the onset of a major depressive disorder. The flashes may also be a clinical sign for underlying cardio vascular disease as well as a risk factor for poor bone heath. Although “natural”, hot flashes are not great to experience and ultimately may correlate with poor overall health.
What we do know is that the peak incidence of hot flashes occurs approximately 1 year after menopause in 80% of women in the US, but (and this is what is so surprising) the overall duration of hot flushes is unclear.

(Sorry that this intro is so long, but now I’ll get to a recent attempt to answer the “how long will this last” question…) A study published in the May issue of Obstetrics and Gynecology tried to assess the duration of menopausal hot flashes and associated risk factors.

The “flushing and flashing” women that were followed were part of The Penn (Pennsylvania) Ovarian Aging Study of 435 women (half white and half African American) that were monitored for 13 years. Hot flushes (they use this term instead of “flash”) were evaluated at 9 -month and 12-month intervals though in-person interviews. At enrollment, the participants’ ages were 35 to 47 (mean age 42.2) and 91% were still premenopausal. The most common age at onset of moderate-to-severe hot flushes was 45-49(35%); 30% were between 40-44years, 21% were older than age 50and 14% were younger than 40 years. Age at the onset was inversely associated with duration of hot flashes. In other words, the younger the women were, the longer they suffered. This totaled 11.57 years for those whose onset of hot flushes occurred before the age of 40; and decreased with onset at older ages: 11.25 years for those whose flushes started at 40 to 44 years; 8.1 years with onset ages 45-59 and 3.8 years duration with onset at 50 years of age or older.

Other independent predictors of the duration of the flushes were race (African Americans had a longer duration) and body mass (thin women also had a longer duration.) It’s thought that obese women convert hormones produced by their adrenals to estrogen-like hormones in their abundant fat and hence have production of estrogen that “saves them” from many years of flushes. It’s interesting that in this study smoking, alcohol use and number of children the women bore had no association with the duration of their hot flushes. (Although in general, the data has shown that smokers enter the menopause at an earlier age than non smokers, simply because the toxins in cigarettes kill off the follicles in the ovaries….my comment in this article against smoking!).

In the discussion portion of the article, the author’s state that “the median duration of moderate-to-severe hot flushes was 10.2 years, well beyond the duration considered in clinical guidelines. When women who reported mild hot flushes were included, the median duration increased to 11.6 years.”

Before all you women who begin to have menopausal symptoms in your early 50′s freak that these will continue unabated into your 60′s, I have to point out that the majority of the women in this study were younger than 50 when they reported moderate-to-sever hot flushes. (Most were 45 to 49.) Hot flush duration was approximately 8 years for this group compared to less than 4 years when onset occurred at ages 50 years or older.

Bottom line: The earlier you begin to have hot flashes (even if you are still getting your period) the longer you can expect them to continue during menopause. Now that you have this information, discuss therapies with your doctor.

In addition to my usual Friday website article, I felt it was necessary to address the recent JAMA article on estrogen-only therapy (in women who have had a hysterectomy.) The women were followed and results have just been published years after the Women’s Health Initiative (WHI) was stopped. The American Menopause Society (NAMS) said it best and hence I am simply forwarding the message that appeared on their website in response to this article. Once more, their conclusions reinforce the fact that estrogen (without a progestin) did not increase, but actually decreased breast cancer, in follow-up of over 10 years. Premarin (CEE) therapy was found to be beneficial vis a vis heart disease, colorectal cancer and overall, all-cause mortality for women under the age of 70 but appeared to lose its benefits and indeed worsen mortality rates after the age of 70. So here is the data and the NAMS conclusion:

Brief summary of the article: The final results of the Women’s Health Initiative Estrogen-Alone Trial, reflecting a median of 6 years of treatment and an average of 10.7 years of follow-up, are published in this article. The long-term follow-up and post-stopping findings for this trial have not been previously reported. The authors examined health outcomes in 10,739 women with prior hysterectomy, comparing those randomized to receive CEE treatment versus placebo. The median duration of adherence (taking >80% of study pills) to CEE was 3.5 years.

The main outcomes were CHD and invasive breast cancer. In addition, a global index of risks and benefits included CHD, stroke, pulmonary embolism, breast cancer, colorectal cancer, hip fracture, and death.

Results: For the overall study population, there was a significantly reduced risk of invasive breast cancer among women randomized to CEE versus placebo over the 10.7 years of follow-up (23% reduction; HR 0.77; 95% CI, 0.62-0.95). Risk reductions were similar in the treatment and post-stopping periods. In the overall study population, there was no significant effect of CEE on CHD, deep vein thrombosis, stroke, hip fracture, colorectal cancer, or total mortality. However, younger women (ages 50-59 at enrollment) tended to have much more favorable outcomes on CEE than the older women for CHD, heart attack, colorectal cancer, all-cause mortality, and the global index. For heart disease endpoints, risks were 40% to 50% lower with CEE than placebo in women ages 50 to 59 but were higher with CEE than placebo in women ages 70 to 79. For example, for every 10,000 women per year taking CEE, there were 12 fewer heart attacks, 13 fewer deaths, and 18 fewer adverse events for women ages 50 to 59. In contrast, for every 10,000 women per year ages 70 to 79, there were 16 extra heart attacks, 19 extra deaths, and 48 extra adverse events for women taking CEE (P values for interaction by age were statistically significant).

Conclusions: In this randomized trial, conjugated equine estrogens (CEE) use was associated with a decreased risk of invasive breast cancer and much more favorable results for coronary heart disease (CHD), all-cause mortality, and several other outcomes in younger than in older women. Overall, the observed pattern provides more support for the “timing hypothesis.” The findings highlight the differences between estrogen alone and estrogen plus progestin in terms of breast cancer risk and other chronic disease outcomes, as well as important differences by age group. Whether the reduction in breast cancer risk with CEE alone will apply to all women at menopause and to estradiol or other formulations of estrogen, and whether it will persist with longer-term estrogen use, remains unknown.