oestrogen

SYN: estrogen.

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n.

one of a group of steroid hormones (including oestriol, oestrone, and oestradiol) that control female sexual development, promoting the growth and function of the female sex organs (see menstrual cycle) and female secondary sexual characteristics (such as breast development). Oestrogens are synthesized mainly by the ovary; small amounts are also produced by the adrenal cortex, testes, and placenta. In men excessive production of oestrogen gives rise to feminization.

Naturally occurring and synthetic oestrogens, given by mouth or injection, are used to treat amenorrhoea and menopausal symptoms (see hormone replacement therapy), as well as androgen-dependent cancers (e.g. cancer of the prostate), and also to inhibit lactation. Synthetic oestrogens are a major constituent of oral contraceptive. Side-effects of oestrogen therapy may include nausea and vomiting, headache and dizziness, irregular vaginal bleeding, fluid and salt retention, and feminization in men. Oestrogens should not be used in patients with a history of cancer of the breast, uterus, or genital tract.

• oestrogenic adj.