Menopause
Menopause
Mantophasmatodea
Technically, menopause refers to the ceasing of menses; whereas the gradual process through which this occurs, which typically takes a year but may last as little as six months or more than five years, is known as climacteric. Popular use, however, replaces climacteric with menopause. Menopause can either be natural or surgically induced. A natural or physiological menopause refers to the ceasing of menses that is a part of a woman's normal ageing process. However, a surgically induced menopause refers to the ceasing of menses for reasons such as because the woman has had a previous Hysterectomy.
The average onset of menopause is 50.5 years, but some women enter menopause at a younger age, especially if they have suffered from Cancer or another serious illness and undergone Chemotherapy. Premature menopause (or Premature Ovarian Failure) is defined as menopause occurring before the age of 40, and occurs in 1% of women. Other causes of premature menopause include autoimmune disorders like Thyroid disease or Diabetes mellitus. Premature menopause is diagnosed by measuring the levels of follicle stimulating hormone (FSH) and Luteinizing hormone (LH); the levels of these hormones will be higher if menopause has occurred. Rates of premature menopause have been found to be significantly higher in both fraternal and identical twins; approximately 5% of twins reach menopause before the age of 40. The reasons for this are not completely understood. Cases of transplant of ovarian tissue between identical twins have been successful in restoring fertility.
Post-menopausal women, especially Europeans, are at increased risk of osteoporosis.
Menopause is rare in animal species. One possible explanation for its evolution in humans is the Grandmother hypothesis.
See also: Teriparatide, Andropause (a similar process in men).