, occurring in both human sex
es and affecting mood
characteristics, best mainly known as the most important female sex hormone
. It is named from its ability to produce oestrus
in animals, and is also spelt estrogen
There are three naturally occurring forms of oestrogen in women:
When oestrogen is at its highest level in the blood, follicle
s release egg
s. As well as regulating primary and sexual characteristic
s it regulate
s secondary ones such as the distribution of body fat
. Falling levels of oestrogen may be linked with mood alternations such as PMT
, post-natal depression
, and menopausal depression
There are also environmental oestrogens, including phytoestrogens such as those in tofu and broccoli, synthetic oestrogens such as ethinyl oestradiol (EE), prescribed oestrogens such as the contraceptive pill, residues in drinking water, and pesticides. Some of these may be toxic in the sense that they are associated with higher levels of cancer.
A hysterectomy removing the ovaries means oestrogen is not produced in sufficient quantities, so in this case the hormone is the one used in HRT. It may be used alone or with progestin.