Hormones in POI

1. Oestrogen (mainly Estradiol, E2)

Role in the female body:

·      Maintains the menstrual cycle by building up the endometrial lining each month.

·      Essential for bone strength (prevents osteoporosis).

·      Supports cardiovascular health by maintaining good cholesterol balance and vascular function.

·      Affects the brain and mood (neuroprotection, memory, sleep, emotional regulation).

·      Important for urogenital health (keeps vaginal tissue healthy, prevents dryness).

In POI:

·      Oestrogen levels are low, because the ovaries are not producing it regularly.

·      This leads to irregular/absent periods, infertility, bone loss, hot flushes, night sweats, and vaginal dryness.

2. Progesterone

Role in the female body:

·       Produced after ovulation by the corpus luteum.

·       Balances oestrogen by stabilising the endometrium (prepares it for pregnancy, prevents overgrowth).

·       Regulates the menstrual cycle (withdrawal of progesterone = period).

·       Has effects on mood and sleep.

In POI:

·      Without ovulation, progesterone is often low or absent.

·      This causes irregular or missed cycles and may contribute to endometrial hyperplasia if oestrogen replacement is not properly balanced with progesterone.

·      In women on hormone replacement therapy (HRT), progesterone (or a progestogen) is given to protect the womb lining if they still have a uterus.

3. Testosterone (and other androgens like DHEA)

Role in the female body:

·       Though usually thought of as a “male” hormone, women produce small amounts in the ovaries and adrenal glands.

·       Important for sexual desire and arousal.

·       Contributes to muscle mass, bone density, and energy levels.

·       Supports cognitive function and wellbeing.

In POI:

·      Testosterone may also be low, because ovarian androgen production is reduced.

·      This can lead to low libido, fatigue, and reduced quality of life in some women.

·      Some clinicians may consider androgen therapy (testosterone or DHEA) in selected cases, though evidence is mixed and it’s not standard in all guidelines.

4. LH (Luteinising Hormone)

Role in the female body:

·      Released from pituitary.

·      Works with FSH to drive follicle growth.

·      Mid-cycle surge triggers ovulation.

·      Stimulates theca cells to make androgens (testosterone, converted to oestrogen in granulosa cells).

In POI:

·      Often raised (though less reliable than FSH for diagnosis).

·      Because ovulation rarely occurs, the LH surge is absent, so regular ovulation is lost.

·      This contributes to infertility and irregular/absent cycles.

5. FSH (Follicle Stimulating Hormone)

Role in the female body:

·      Produced by the pituitary gland.

·      Stimulates the ovarian follicles to grow and produce oestrogen.

·      Works alongside LH (luteinising hormone) to control ovulation.

In POI:

·       Because the ovaries are failing and not producing enough oestrogen, the brain keeps sending stronger signals to stimulate them.

·       This means FSH is persistently high (≥25 IU/L on two occasions, 4–6 weeks apart — a diagnostic criterion for POI).

·       High FSH is a marker of ovarian insufficiency, not a cause.

6. AMH (Anti-Müllerian Hormone)

Role in the female body:

·       Produced by small growing ovarian follicles.

·       Reflects the “ovarian reserve” (number of remaining eggs).

·       Used as a marker in fertility assessments.

In POI:

·      AMH is usually very low or undetectable, indicating depletion of ovarian reserve.

·      Not essential for diagnosis (FSH + menstrual history are key), but it can give additional information about fertility potential.