Premature Menopause - menopause occurring before the age of 40 years.

This is an arbitrary cut off point designated by the World Health Organisation (WHO); ideally premature menopause should be defined as menopause occurring at an age two standard deviations below the population mean. This term includes both spontaneous and induced menopause (defined by the WHO as the cessation of menses following oophorectomy or chemotherapy/ radiotherapy -induced ablation of ovarian function).

Premature ovarian failure (POF) - cessation of ovarian function associated with amenorrhoea and elevated gonadotrophins occurring in women less than 40 years of age.

There is debate within the literature as to whether premature ovarian failure (POF) should refer only to spontaneous cessation of ovarian function and exclude induced ovarian failure. Premature ovarian dysfunction, has been proposed as a substitute for POF due to the negative connotation associated with the word "failure" and the potential for recovery of ovarian function, but is not commonly applied. In practice, premature menopause and POF are often used interchangeably.

Early Menopause - menopause occurring between the age of 40 - 45 years.

This is not a WHO proposed definition but has been used in studies to describe a population of women in whom menopause occurs earlier than 45 years (the lower limit of the normal population range)

Resistant ovary syndrome

A rare condition characterised by elevated FSH levels in the presence of normal ovarian follicles on biopsy.

Normal ovarian development and pathophysiology of Premature Menopause

Current evidence suggests that during fetal maturation a finite number of ovarian germ cells develop; peaking at 6 million by gestational week 20 and then declining via the process of apoptosis (programmed cell death) so that approximately 1 million exist in each ovary at birth. The majority of ovarian follicles (oocyte with surrounding granulosa cells) undergo a process of degeneration (atresia); a process that continues throughout life. Thus, at puberty approximately 300,000 oocytes remain, of which only 400-500 follicles will develop fully and ovulate during the woman's reproductive life span. Menopause occurs when the pool of follicles is exhausted. The mechanisms controlling follicle development and atresia remain unclear. The pathophysiological mechanisms leading to premature menopause/early menopause may involve follicle depletion (deficient initial follicle number and/or accelerated follicle atresia) or ovarian follicle dysfunction.

The characteristic hormonal profile of a woman with premature menopause is elevated gonadotrophins, low oestradiol and low inhibin B. Androgen levels in women with premature menopause are reduced. Bilateral oophorectomy results in a dramatic drop in circulating oestrogens and androgens within 24 hours of surgery.

Content updated December 09, 2007