Last reviewed 01/2018

Oestrogen production in a male may cause gynaecomastia.

Unopposed oestrogen stimulation of the endometrium, i.e. oestrogen stimulation without a period of progesterone stimulation and consequent menses, is associated with the development of endometrial carcinoma.

Unopposed oestrogen stimulation of the endometrium occurs in conditions such as thecal cell tumours of the ovary. Old regimes of hormone replacement therapy used oestrogen only preparations without periods of progestogen use. This is not the case today, where mixed oestrogen and progestogen regimes are used.