Menopause is defined as the permanent cessation of menses due to declining ovarian estrogen production, diagnosed retrospectively after 12 consecutive months of amenorrhea, whereas perimenopause (the climacteric) is the transitional period of 2–8 years marked by menstrual irregularity as ovarian follicular reserve declines through atresia. This transition is driven by a defined hormonal cascade: declining estradiol and inhibin B from diminishing follicles lead to rising FSH and LH, while aromatase-mediated peripheral conversion shifts the dominant estrogen from estradiol to estrone, with anti-mullerian hormone and inhibin B serving as earlier declining markers of ovarian reserve. This is a core topic in gynecologic endocrinology describing the physiologic transition from reproductive to nonreproductive hormonal states.
Menopause is defined as the permanent cessation of menses due to declining ovarian estrogen production, diagnosed retrospectively after 12 consecutive months of amenorrhea, whereas perimenopause (the…