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Sexual Steroid Hormones
Medical expert of the article
Last reviewed: 23.04.2024
By biological action, as well as the sequence and number of carbon atoms (18, 19, 21) in their molecules, sex steroids are divided into three main groups.
- From 18 - estrogens (the main representative - estradiol, estrone, estriol).
- With 19 - androgens (the main representative is testosterone).
- With 21 - gestagens (the main representative is progesterone).
In the female body, the most important sex steroids are formed in the ovaries and adrenal cortex, and during pregnancy - in the placenta. The main sex steroids of the male body (androgens) are synthesized in the testicles and, in a small amount, in the adrenal cortex.
All sex steroids and hormones of the adrenal cortex are derived from cholesterol. Steroids are lipophilic, which causes their low solubility in water, so in blood 95% of steroid hormones are in a bound state with specific transport proteins. With the help of transport proteins, hormones are transferred to their target organs. Only free, non-protein-bound steroids have a biological effect. Steroid binding globulin (SSH) specifically binds estradiol and androgens with high affinity, while corticosteroid-binding globulin binds progesterone and glucocorticosteroids. In addition to its transport function, hormone-binding proteins protect steroids from metabolic inactivation along the way from the secreting gland to the target organ.
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