1)Natural Menopause

Fertility and ovarian mass declines sharply after the age of 35 years. There is depletion of primary follicles (a process that begins before birth) steadily until menopause.

The primodial follicles are about 1.5 million at birth. Most of these primodial follicles become atretic. Only about 400 to 400,000 follicles at puberty will progress to ovulation.

It is important to note that the circulating estradiol in a premenopausal woman is produced by these developing follicles. The granulosa cells which form the internal lining of the follicles converts testosterone and androstenedione to oestradiol. This conversion is catalyzed by the aromatase enzyme cascade which is promoted by FSH (follicle stimulating hormone). The theca cells also produces estradiol from androgens and the process is stimulated by LH (Leuteinizing hormone).

2)Surgical Menopause

If the ovaries are removed surgically, there is immediate onset of menopause.

Patients who have undergone hysterectomy are also likely to suffer from premature  menopause, even if their ovaries are conserved during the surgery. In hysterectomised patients the median age of menopause advances by about 2 to 3 years.

There is continued debate as to weather oophorectomy should accompany hysterectomy in women over the age of 45. This could prevent ovarian cancer.

This abrupt decrease in the hormones can result in severe vasomotor symptoms(eg hot flushes) and rapid onset of dyspareunia (pain during coitus) and osteoporosis if not treated immediately.estrogen replacement therapy should be started immediately after surgery. Conjugated 1.25mg,estrone sulphate 1.25mg or estradiol 2mg should be given for 25 days of each month. After the age of45-50 years this dose should be tapered off to 0.625mg of conjugated estrogens (or equivalent).

3)Premature ovarian failure

This is also an important cause of menopause.

Premature ovarian failure is defined as failure of the ovary before the age of 45 years to generate estrogen leading to secondary amenorrhoea. Patients also have symptoms other symptoms suggestive of estrogen deficiency.

Lab tests reveal a low plasma E2 (less than 150pmol/L and high levels of follicle stimulating hormone (FSH), luteinizing hormone (LH).

On microscopic examination of the ovary in premature ovarian failure, it appears like a postmenopausal ovary.

In resistant ovary syndrome the biological appearances of the ovary are normal, with abundant primodial follicles

4) Other causes of Menopause

The management of malignant diseases in young women may induce menopause. In fact radiation of the ovary is used to suppress estrogen output from the ovary (This will soon be replaced by estrogen antagonists in the future).

Chemotherapeutic drugs used in the management of cancer (er breast cancer), lymphomas etc may suppress and arrest ovarian cyclic activity. Patients who are going in for such treatments must be counseled properly, before consent is obtained for treatment.

References:

Pages 2209 to 2212.Chapter 327. The menopause transition and postmenopausal hormone therapy.Harrisons Principles of Internal Medicine. Volume II.16th edition. Kasper,Braunwald,Fauci,Hauser,Longo and Jameson.

Pages 227 to 229. Chapter 19. Menopause. Gynaecology by ten teachers. Seventeenth edition. Edited by Stuart Campbell and Ash Monga.

Pages 760 to 762. Chapter 17. Menopausal syndrome.Gynaecology. CMDT 2006. Current Medical Diagnosis and Treatment 2006.45 th Edition. Edited by Lawrence M. Tierney,Jr. Stephen J McPhee, Maxine A. Papadakis.

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