Menopause and premature ovarian failure

Published on 09/03/2015 by admin

Filed under Obstetrics & Gynecology

Last modified 09/03/2015

Print this page

This article have been viewed 1136 times

Chapter 12 Menopause and premature ovarian failure

Definitions. Natural menopause is the permanent ceasing of menstruation resulting from the loss of ovarian follicular activity. Menopause is by definition only after 12 months of amenorrhoea with no other pathological cause. Menopause is the final period diagnosed only in retrospect. Perimenopause is the time immediately premenopause, as characterised by endocrinological and clinical features, and continuing until the year postmenopause. Premature menopause occurs at an age <2 standard deviations from the community mean. In practice, this is menopause prior to the age of 40. The average age of menopause is 50–51 years.

Aetiology

Menopause is due to the exhaustion of primordial follicles, causing a fall in oestrogen and progesterone levels.

Endocrinology in the climacteric and menopause

Three phases of endocrine changes

• hypothalamic–pituitary hyperactivity occurring years before and continuing after menopause

• ovulatory failure

• ovarian follicular failure

Initial changes in ovarian function are due to a failure in ovulation and a deficient luteal phase. Following this is a reduction in serum oestradiol and a rise in follicle-stimulating hormone (FSH) due to the negative hormonal feedback. Rises in luteinising hormone (LH) occur later, but these are not as marked as the rise in FSH. Follicular development and menstrual cycles then become irregular. At menopause, insufficient ovarian follicular development results in insufficient oestrogen to cause endometrial growth. In the postmenopausal state, oestradiol decreases with a normal or slightly raised level of oestrone.

Gonadotrophins after the menopause

• Maximal rises in FSH and LH occur in the first 2–3 years.

• After 20 years, FSH and LH may return to reproductive life levels.

Oestrogens

• Postmenopausal oestrogen sources are derived from the peripheral conversion of androstenedione (produced by the adrenals and ovaries) to oestrone.

• Aromatisation of androstenedione occurs at peripheral sites.

Androgens

• Ovaries continue to secrete androgens: androstenedione and testosterone.

Progesterone

• Levels are lower than premenopausal levels.

Others

• Prolactin levels decrease.

• Inhibin has a specific negative feedback control on FSH and levels are reduced.

Clinical features of menopause

Generally, clinical features are the best guide to menopause: 10%–20% have no symptoms; 60% have mild to moderate symptoms; and 10%–20% have severe symptoms. While vasomotor symptoms predominate, they are not necessary and symptoms are variable. Symptoms are relieved by oestrogen.

Vasomotor symptoms

• A hot flush lasts between 1 and 4 minutes and is associated with a rise in temperature, peripheral vasodilatation and a slight rise in pulse rate.

• There is a possible association with rising and falling oestrogen levels.

• Hot flushes are synchronous with, but are not caused by, LH pulses.

Buy Membership for Obstetrics & Gynecology Category to continue reading. Learn more here

Related

Examination Obstetrics _ Gynaecology