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[Physiology](https://durgical.com/en/physiology/) · [Reproduction, pregnancy and the fetus](https://durgical.com/en/physiology/#s-repro)

# Menopause

- Regulation
- Exam priority: medium

Menopause is the end of periods when the ovaries run out of follicles; estrogen falls and the brain's signals to the ovary rise.

Updated 2026-11-01

Also called: Climacteric, Perimenopause

**See it in 3D:** [Ovaries](https://durgical.com/en/anatomy/ovary/) · [Endometrium](https://durgical.com/en/anatomy/endometrium/) · [Vagina](https://durgical.com/en/anatomy/vagina/) · [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/)

## Key points

- Diagnosis is clinical: 12 months of amenorrhea at the expected age (median ≈51 years; often ≈48–50 years in Latin American studies).
- Lab pattern: FSH ↑↑, LH ↑, estradiol ↓, inhibin and AMH ↓ (primary ovarian failure).
- After menopause the main estrogen is estrone, made in fat by aromatization of adrenal androgens.
- Hot flashes come from a narrowed thermoneutral zone in the hypothalamus (neurokinin B / KNDy neurons).
- Bone loss accelerates in the first 5–10 years: the main cause of osteoporosis in women.
- Menopause before 40 years is premature ovarian insufficiency; postmenopausal bleeding always needs evaluation.

## What it is

Menopause is the final menstrual period, confirmed after 12 months without menstruation, caused by depletion of ovarian follicles. As follicles run out, inhibin B and then estradiol fall, so FSH rises (first and most) and LH rises. The perimenopausal years before it bring irregular cycles; the years after, the effects of low estrogen on vessels, bone, the genitourinary tract and temperature control.

## How it works, step by step

- The follicle pool falls with age through atresia; fewer growing follicles make less inhibin B.
- Less inhibin removes the brake on FSH: FSH rises and cycles shorten (faster follicle recruitment).
- Cycles become irregular and often anovulatory: unopposed estrogen phases alternate with low estrogen.
- When follicles are exhausted, estradiol and progesterone fall permanently and menses stop.
- Without estrogen feedback, LH and FSH stay high; estrone from fat becomes the main estrogen.

### Hormone axes and feedback

**Lesion** Ovarian failure (menopause, Turner syndrome) **Pattern** GnRH ↑ · LH ↑ · FSH ↑ · E₂ ↓ · Progest. ↓ · Inhibin ↓

#### Primary hypofunction: Ovarian failure (menopause, Turner syndrome)

**Pattern:** GnRH ↑ · LH ↑ · FSH ↑ · E₂ ↓ · Progest. ↓ · Inhibin ↓

The target gland fails: its hormone falls and, without negative feedback, the pituitary and hypothalamic hormones rise. Estradiol ↓ with FSH ↑ (it rises more than LH, because inhibin is also lost) and LH ↑. Turner (45,X): streak ovaries, primary amenorrhea.

Exam rule: if the pituitary hormone moves opposite to the gland hormone, the problem is in the gland (primary); if they move together, it is central (pituitary or hypothalamus).

- Stimulates (+)
- Inhibits / negative feedback (−)
- Positive feedback (high E₂ at mid-cycle)
- Level ↑
- Level ↓

Ovarian failure: estradiol falls and FSH rises more than LH because inhibin is also gone.

## Typical values

| Parameter | Value | Note |
| --- | --- | --- |
| Age at menopause | ≈48–52 years | median ≈51 years worldwide |
| Definition | 12 months without menses | retrospective |
| Premature ovarian insufficiency | 25–40 IU/L | laboratory cut-offs vary |

Approximate values for a healthy adult at rest; each laboratory sets its own ranges.

## Regulation

- *−* **Loss of inhibin B (fewer follicles)**: FSH rises early, before estradiol falls.
- *−* **Loss of estradiol and progesterone**: No negative feedback: LH and FSH remain high.
- *+* **Aromatase in fat tissue**: Estrone from adrenal androgens; more fat means more estrone.

## Effects of low estrogen

| Target | Change | Consequence |
| --- | --- | --- |
| Hypothalamus | Narrow thermoneutral zone | Hot flashes, night sweats, poor sleep |
| [Bone](https://durgical.com/en/conditions/osteoporosis/) | More resorption | Osteoporosis, fractures |
| Vagina and urethra | Thin epithelium, less glycogen, higher pH | Dryness, dyspareunia, urinary infections |
| Lipids and vessels | Higher LDL, less vasodilation | Rise in cardiovascular risk |
| [Endometrium](https://durgical.com/en/conditions/endometrial-cancer/) | Atrophy | Any bleeding after menopause needs study |

## Clinical notes

- Turner syndrome (45,X) causes ovarian failure from childhood: primary amenorrhea with high FSH.
- Bleeding after menopause can come from atrophy, polyps, hyperplasia or endometrial cancer and is always investigated.
- Estrogen therapy in women with a uterus is combined with a progestogen, because unopposed estrogen causes endometrial hyperplasia.

## Memory aid

No follicles, no brakes: FSH Flies first, LH follows.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does FSH rise before LH in the menopausal transition?

The first change is loss of inhibin B from the shrinking follicle pool; inhibin selectively restrains FSH, so FSH rises while estradiol is still present.

## Where does a postmenopausal woman's estrogen come from?

Mainly estrone, made by aromatase in fat tissue from adrenal androstenedione; obesity therefore raises postmenopausal estrogen and endometrial cancer risk.

## Why does bone density fall quickly after menopause?

Estrogen restrains osteoclast formation and activity (via RANKL/OPG); its loss increases resorption more than formation.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/physiology/menopause/)

## See it in 3D

The structures of Durgical's 3D anatomy where it happens.

- [Ovaries](https://durgical.com/en/anatomy/ovary/)
- [Endometrium](https://durgical.com/en/anatomy/endometrium/)
- [Vagina](https://durgical.com/en/anatomy/vagina/)
- [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/)

## Related topics

- [Actions of estrogen and progesterone](https://durgical.com/en/physiology/actions-of-estrogen-and-progesterone/)
- [The menstrual cycle: ovary and endometrium](https://durgical.com/en/physiology/the-menstrual-cycle-ovary-and-endometrium/)
- [Bone remodeling](https://durgical.com/en/physiology/bone-remodeling/)
- [Oogenesis, follicles and ovulation](https://durgical.com/en/physiology/oogenesis-follicles-and-ovulation/)
- [Body temperature regulation](https://durgical.com/en/physiology/body-temperature-regulation/)

## Related conditions

- [Osteoporosis](https://durgical.com/en/conditions/osteoporosis/)
- [Abnormal uterine bleeding](https://durgical.com/en/conditions/abnormal-uterine-bleeding/)
- [Endometrial cancer](https://durgical.com/en/conditions/endometrial-cancer/)

## In Biochemistry

- [Aromatase (CYP19A1)](https://durgical.com/en/biochemistry/enzymes/aromatase/)

[← All of physiology](https://durgical.com/en/physiology/)

Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Sources: [27.2 Anatomy and Physiology of the Ovarian Reproductive System](https://openstax.org/books/anatomy-and-physiology-2e/pages/27-2-anatomy-and-physiology-of-the-ovarian-reproductive-system/) (OpenStax (Rice University), 2022); [Osteoporosis in Females](https://www.ncbi.nlm.nih.gov/books/NBK559156/) (StatPearls (NCBI Bookshelf), 2025); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 82). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/physiology/menopause/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/menopause/