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.