Expansion
Ovarian follicle depletion causes low oestrogen with high FSH and LH
Expansion
Mechanism: the ovarian follicle pool is exhausted, so oestrogen and inhibin fall and the negative feedback on the pituitary is lost.
- FSH rises first and most, because inhibin B specifically restrains FSH and falls earliest
- LH also rises, though less
- Oestradiol falls; the remaining oestrogen is mainly oestrone from peripheral aromatisation of adrenal androgens in adipose tissue
Definition: 12 months of amenorrhoea, average age 51.
Consequences
- Vasomotor: hot flushes and night sweats, from altered hypothalamic thermoregulation
- Urogenital atrophy: dryness, dyspareunia, urinary symptoms. Unlike the vasomotor symptoms, this does not improve with time and is often progressive
- Bone: accelerated loss of up to 3 per cent a year in the first few years, since oestrogen restrains osteoclasts through the RANK ligand system
- Cardiovascular risk rises
Hormone replacement is effective for vasomotor and urogenital symptoms and protects bone. Women with a uterus must receive a progestogen alongside oestrogen, since unopposed oestrogen causes endometrial hyperplasia and carcinoma.