Professor Rodney Baber AM
Clinical Professor of Obstetrics and Gynaecology, Faculty of Medicine and Health, The University of Sydney
Past President IMS
Editor in Chief, Climacteric
Associate Editor ANZJOG
Progestogens are defined as substances which bind to the progesterone receptors and exert an agonistic response. They may be divided into two major categories: natural and synthetic.
Progesterone is the only natural progestogen. Synthetic progestogens, also known as progestins are derived from testosterone derivatives, hydroxyprogesterone derivatives and spironolactone.
The principal indication for the use of progestogens on MHT is to prevent estrogen induced endometrial hyperplasia and cancer.
The effect of progestogens on an estrogen primed endometrium depends on the dosage, duration of exposure and the type of progestogen chosen.
For commonly used, ‘average’ doses of estrogen there is clear evidence of the appropriate dose and duration of therapy required for different progestogens. However, for higher doses of estrogen the doses are less clearly defined.
Whilst progesterone binds almost exclusively to the progesterone receptors, synthetic progestins also bind to other steroid hormone receptors, an effect related to their origins.
The consequence of progestins binding to other steroid receptors may be associated with adverse effects on cardiovascular and breast health.
These effects and an approach to appropriate use of progestogens will be discussed.