Overview

Median age≈51 years

Diagnosis12 months of amenorrhoea

Premature<40 years (early: 40–45)

As the follicle pool falls towards ≈1000, fewer follicles respond each cycle. Inhibin B falls first, so FSH rises while estradiol may initially be normal or even high; cycles become irregular (the menopausal transition or perimenopause, lasting ≈4–5 years). Eventually follicles are exhausted, estradiol and progesterone fall to low levels, FSH and LH rise markedly (loss of negative feedback) and AMH becomes undetectable. After menopause the main estrogen is estrone, formed by aromatisation of adrenal androstenedione in adipose tissue.

Symptoms reflect estrogen deficiency: vasomotor symptoms (hot flushes and night sweats in ≈75–80 % of women — due to narrowing of the hypothalamic thermoneutral zone driven by KNDy neuron hyperactivity), sleep disturbance, mood change, joint pains, reduced libido and the genitourinary syndrome of menopause (vaginal dryness, dyspareunia, urgency, recurrent UTIs). Long-term, accelerated bone loss raises the risk of osteoporosis and fractures, and cardiovascular risk increases.

Location: Ovaries (follicle exhaustion), with systemic effects.

Function

Marks the end of the reproductive lifespan.

Physiology: Diagnosis is clinical in women over 45 with typical symptoms; FSH (>≈30 IU/L) is used when younger. Ovarian androgen production continues from stromal and hilus cells.

Clinical significance

Hormone replacement therapy (HRT)

Estrogen relieves vasomotor and genitourinary symptoms and prevents bone loss; women with a uterus also need a progestogen to protect the endometrium. Transdermal estrogen does not raise VTE risk; combined HRT slightly increases breast cancer risk with duration. Local vaginal estrogen treats genitourinary symptoms. Non-hormonal options include SSRIs/SNRIs and neurokinin-3 receptor antagonists (fezolinetant).

Premature ovarian insufficiency

Menopause before 40 (≈1 %): Turner syndrome, fragile X premutation, autoimmune disease, chemotherapy or radiotherapy, surgery, or idiopathic. Hormone replacement is recommended until the natural age of menopause to protect bone and heart.

Postmenopausal bleeding

Any bleeding after menopause requires investigation (transvaginal ultrasound ± endometrial biopsy) to exclude endometrial carcinoma.

Test yourself

Which hormone profile best indicates menopause?

Low FSH, low estradiol
High FSH, low estradiol
High estradiol, low LH
High prolactin, low FSH

Answer: High FSH, low estradiol

With follicle depletion, inhibin B and estradiol fall, so negative feedback is lost and FSH (then LH) rises — the hallmark of primary ovarian failure. Low FSH with low estradiol suggests hypothalamic or pituitary disease.