Menopause is the stage of life when menses permanently cease, and the reproductive system no longer performs functions related to fertility. A woman is considered to have entered menopause after menses have stopped for 12 months.
Last Updated: October 20 2021
Natural menopause generally occurs between the ages of 40 to 58 and has no obvious pathological or physiological cause, but early menopause can result from surgery, chemotherapy, radiotherapy, or primary ovarian insufficiency. Perimenopause is the transitional phase into menopause and may last between 4 to 8 years. During this phase, menstrual periods become irregular due to fluctuating hormone levels.
For this page, we use the generic term 'woman', but this information can apply to anyone with ovaries and/or who might be undergoing a hormonal shift associated with the symptoms of menopause.
Menopause is a natural condition that occurs as women age. Over time, a woman’s ovarian follicles and granulosa cells diminish. Given these cells are the main producers of estradiol and inhibin(a hormone that tells the pituitary gland to make less follicle stimulating hormone), the body’s hormonal balance shifts toward lower estrogen levels and increased follicle-stimulating hormone and luteinizing hormone levels. This hormonal profile results in irregular menstrual cycles, which ultimately stop altogether. One clinical indicator that a woman is postmenopausal is a follicle-stimulating hormone level greater than 30 mIU/mL and an estradiol level under 30 pg/m.
Hormonal variations across a woman's lifetime
Primary ovarian insufficiency (POI) is a condition often characterized by entering menopause at a young age (i.e. prior to 40 years). There are a variety of causes that underlie POI, but the main one is estrogen deficiency. Other factors that play a role in POI are genetic disorders, autoimmune disease, chemotherapy, radiotherapy, and metabolic disorders. Smoking has also been associated with early menopause.
Hot flashes, night sweats, vaginal dryness, insomnia, trouble focusing, and mood swings are the primary symptoms women experience during the transition into and sometimes throughout menopause. Women can also experience changes in body composition. The majority of these symptoms are a result of hormonal fluctuations accompanying the decline to infertility, with hot flashes among the most commonly reported.
In fact, as many as half of all women report experiencing hot flashes even before they cease menstruating. Hot flashes peak during the later phases of the menopausal transition, tapering off in late menopause. Women tend to experience these symptoms for roughly five years.
Changes in vaginal tissue resulting from decreased estrogen account for a number of other commonly reported symptoms, including an increase in urinary tract infections, vaginal atrophy, burning, urinary incontinence, and discomfort during intercourse. Moreover, these changes in hormone levels after menopause affect metabolic processes that can increase the risk of cardiovascular disease, osteoporosis, and stroke.
Regarding changes in body composition, the transition into menopause marks a time when women are particularly prone to gaining fat and losing lean mass. Later onset of menopause seems to temper this increase in weight and body fat. Hormonal changes also tend to shift body fat distribution from a gynoid pattern (body fat around the hips and buttocks) to a more android pattern (body fat around the midsection).
Menopause is clinically diagnosed after 12 months of amenorrhea without other causes, such as surgical removal of the ovaries, chemotherapy or radiotherapy, or POI. It usually occurs after 45 years of age (median age of 51.4 years) and is considered abnormal if it occurs prior to 40 years of age. The diagnosis does not require hormone testing.
In cases where an alternative diagnosis is suspected, such as in women below the age of 45 or in women with thyroid disorders, the following hormone tests can be performed to predict or diagnose the onset of menopause:
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