Progestogens and the menopause

Abstract

Humans are almost unique in nature, having a long post-menopausal life span without ovarian steroid hormones. Most female organs possess estrogen receptors and many have progesterone receptors, implying that these organs are influenced by sex hormones even after cessation of ovarian steropidogenesis. Due to the side effects of estrogen withdrawal at the menopause, estrogen replacement therapy has been widely used for the past 50 years. However, due to the proliferative effect of estrogen on the endometrium leading to hyperplasia and cancer, progestogens are added to counteract the effect of estrogen on the endometrium. However, progestogens have their beneficial and side effects. The main side effect of progestogens is breast cancer as described in Chap. 11. The main side effects of the menopause are osteoporosis and hot flushes. Progestogens have a minimal effect on bone mineral density, but act synergistically with estrogen to reduce hot flushes. Additionally, progestogens, particularly those with antiestrogenic actions, reduces the increased risk of venous thrombo-embolus which is associated with estrogens. Progesterone is a neurosteroid, in addition to its reproductive function. As such it is neuroprotective preventing demyelinization in the central and peripheral nervous systems, and protects against Alzheimer’s disease. In this chapter some of the scientific data that connects progestogens to effects of the menopause are discussed.