This is normal menopause (FA2020 p636). Average age of onset is 51 years (our woman is 52). Hot flashes are a common symptom.
In menopause, the ovaries stop secreting estrogen (17beta-estradiol is an estrogen) due to a decline in the number of ovarian follicles with age. FSH is increased because the feedback inhibition is removed. The source of estrogen after menopause becomes peripheral conversion of androgens.