https://menopause.org/patient-education/the-menopause-guidebook

• Menopause: final menstrual period
• Perimenopause: 4-8 year transitional stage of increasingly irregular periods up to final menstrual period, and the first 12 months following the final period.
• Post-menopausal: After 12 months of amenorrhoea

Demographics: 45-55yo, 51 median age.

• <40yo = primary ovarian insufficiency/ premature menopause
• 40-50 “early menopause”

Aetiology

Age -> ovarian follicles diminish in number. There is a decline in granulosa cells of the ovary, which were the main producers of estradiol and inhibin. With the lack of inhibition from estrogen and inhibin on gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) nproduction increases. FSH levels are usually higher than LH levels because LH is cleared from the blood faster. The decline in estrogen levels disrupts the hypothalamic-pituitary-ovarian axis. As a result, a failure of endometrial development occurs, causing irregular menstrual cycles until they stop altogether.

pathophysiology

• Normal process in aging women: ovarian primary follicles diminish -> cannot respond to FSH -> no LH surge -> no ovulation -> decline of estrogen production and the cessation of menstruation.
• LH and FSH go uninhibited and remain at high levels years after the onset of menopause.
• Small amounts of estrogen may still be produced via conversion from testosterone released by the adrenal glands, such that symptoms other than the discontinuation of periods may be negligible in some individuals

risk factors