Primary ovarian insufficiency (POI)

Primary ovarian insufficiency is loss of normal ovarian function before age 40, affecting about 1 in 100 women. The ovaries produce too little estrogen and release eggs irregularly or not at all, so periods become irregular then stop. Blood tests show the menopausal pattern — high FSH with low estradiol — usually with a low AMH. It differs from ordinary menopause in two ways: it happens early, and it can be intermittent, so occasional ovulation and even pregnancy remain possible, which is why it is called 'insufficiency' rather than 'failure'. Causes include genetic conditions (such as Turner syndrome or fragile-X premutation), autoimmune disease, and damage from chemotherapy, radiotherapy or ovarian surgery, but in many women no cause is found. Because estrogen protects bone and the cardiovascular system, losing it decades early carries long-term health consequences that treatment addresses.

• FSH — raised into the menopausal range, ideally confirmed on two samples weeks apart.
• Estradiol — low.
• AMH — low or undetectable, reflecting depleted ovarian reserve.
• LH — also raised.
• Prolactin, TSH — checked to exclude other causes of absent periods.
• Karyotype, fragile-X (FMR1), adrenal/thyroid antibodies — to find a genetic or autoimmune cause.
• Bone density (DEXA), lipids — baseline for the long-term consequences of early estrogen loss.

• Irregular, infrequent or absent periods before age 40
• Hot flushes and night sweats
• Vaginal dryness, discomfort with sex
• Difficulty conceiving
• Low mood, anxiety, poor sleep
• Reduced libido
• Longer term: accelerated bone loss and higher cardiovascular risk from early estrogen deficiency