Bone health in estrogen-free contraception.

Estrogens and progestogens influence the bone. The major physiological effect of estrogen is the inhibition of bone resorption whereas progestogens exert activity through binding to specific progesterone receptors. New estrogen-free contraceptive and its possible implication on bone turnover are discussed in this review. Insufficient bone acquisition during development and/or accelerated bone loss after attainment of peak bone mass (PBM) are 2 processes that may predispose to fragility fractures in later life. The relative importance of bone acquisition during growth versus bone loss during adulthood for fracture risk has been explored by examining the variability of areal bone mineral density (BMD) (aBMD) values in relation to age. Bone mass acquired at the end of the growth period appears to be more important than bone loss occurring during adult life. The major physiological effect of estrogen is the inhibition of bone resorption. When estrogen transcription possesses binds to the receptors, various genes are activated, and a variety modified. Interleukin 6 (IL-6) stimulates bone resorption, and estrogen blocks osteoblast synthesis of IL-6. Estrogen may also antagonize the IL-6 receptors. Additionally, estrogen inhibits bone resorption by inducing small but cumulative changes in multiple estrogen-dependent regulatory factors including TNF-α and the OPG/RANKL/RANK system. Review on existing data including information about new estrogen-free contraceptives. All progestins exert activity through binding to specific progesterone receptors; hereby, three different groups of progestins exist: pregnanes, gonanes, and estranges. Progestins also comprise specific glucocorticoid, androgen, or mineralocorticoid receptor interactions. Anabolic action of a progestogen may be affected via androgenic, anti-androgenic, or synadrogenic activity. The C 19 nortestosterone class of progestogens is known to bind with more affinity to androgen receptors than the C21 progestins. This article reviews the effect of estrogens and progestogens on bone and presents new data of the currently approved drospirenone-only pill. The use of progestin-only contraceptives leading to an estradiol level between 30 and 50 pg/ml does not seem to lead to an accelerate bone loss.