| Actions of steroid hormones in the female
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In a woman with a normal menstrual cycle, it is the progesterone level that is of diagnostic significance
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| The concentrations of FSH, LH, estradiol, and progesterone vary considerably during the menstrual cycle. In a normally cycling woman it is only progesterone that is of diagnostic significance: a serum concentration of more than 20 nmol/L in the luteal phase is consistent with ovulation. The production rate of estradiol is 80 μg/day early in the cycle rising 10-fold during the follicular phase. In contrast the production rate of progesterone is 2 mg/day in the follicular phase and 10-fold greater in the luteal phase. Estradiol binds to SHBG in plasma, although with a lower affinity than testosterone. Progesterone binds to CBG in plasma with a lower affinity than cortisol.
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| Aside from their roles in the menstrual cycle and reproduction, both estradiol and progesterone have other effects, acting via their specific nuclear receptors in target cells. Estradiol, working in tandem with other hormones such as insulin-like growth factor-I (IGF-I), is responsible for linear growth, breast development and maturation of the urogenital tract and the female habitus. In adult life, both estradiol and progesterone support breast function, and estradiol has an important role in influencing bone turnover. Progesterone is responsible for the rise in basal body temperature during the luteal phase of the menstrual cycle and decreases in progesterone secretion may contribute to changes in mood as seen in premenstrual tension.
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