Description
Progesterone derived from the precursor cholesterol, belongs to the group of steroid hormones called progestins and is the major progestogen in the body involving different functions within the human physiology throughout life.
Progesterone is produced both in men and in women by the adrenal cortex and gonads. In women progesterone is synthesized in different tissues from pregnenolone: in the adrenal cortex, corpus luteum of the ovaries, during pregnancy by the placenta and in small amounts in the adrenal cortex. As a metabolic intermediate, it serves in the production of steroids like aldosterone, cortisol, testosterone and 17β-estradiol, having a variety of crucial functions in the body. Although progesterone is found in women and men, the role in men is less intensive studied, however, it is involved in spermiogenesis, sperm capacitation-acrosome reaction and androgen biosynthesis in Leydig cells. The role of progesterone in women involves the function in ovulation, pregnancy, menstrual cycle and menopause and in this regard, the function of ovaries and placenta. The main part of progesterone can be found as bound to globulin (CBG-corticosteroid binding globulin, Transcortin), to the sex hormone binding globulin (SHBG) and albumin. Only 1 – 2 % of progesterone circulates freely available and presents the active part in plasma. Research has shown that salivary steroids are thought to reflect the concentration of unbound serum steroids; therefore, in this respect, the salivary concentrations may be a better measure of the exposure of target organs to the steroids than with serum concentrations.