Progesteronieritys

Progesteronieritys refers to the production and release of the steroid hormone progesterone by endocrine tissues. In humans, the primary source is the ovaries, where the corpus luteum secretes progesterone after ovulation. During pregnancy the placenta becomes the dominant source of progesterone, supporting the maintenance of gestation. The adrenal glands contribute smaller amounts, and fetal tissues can participate in steroid production under certain conditions.

The secretion of progesterone is regulated by the hypothalamic–pituitary–gonadal axis. Luteinizing hormone (LH) stimulates luteal cells in the ovary to synthesize progesterone. If pregnancy occurs, human chorionic gonadotropin (hCG) from the embryo helps sustain the corpus luteum and its progesterone output until placental production becomes sufficient. Progesterone levels exhibit a marked rise in the luteal phase of the menstrual cycle and then fall if pregnancy does not occur.

Biochemically, progesterone is produced from cholesterol through a series of steps involving mitochondrial cholesterol side-chain cleavage (P450scc/CYP11A1) to pregnenolone, followed by conversion via 3β-hydroxysteroid dehydrogenase (3β-HSD) to progesterone. The hormone is released into the bloodstream, where it binds carrier proteins and is metabolized in the liver with final excretion largely in urine as various metabolites.

Physiological roles include preparing the endometrium for implantation and supporting decidualization, maintaining uterine quiescence during pregnancy, and contributing to breast tissue development. Progesterone also participates in immune modulation and exerts effects through intracellular receptors that regulate gene expression.

Clinical relevance centers on the regulation of progesterone secretion in fertility and pregnancy, luteal-phase disorders, and the use of progesterone or progestins in contraception and assisted reproduction.