estrogenu

Estrogen, sometimes referred to in Romanian as estrogenu, is a group of steroid hormones that regulate development, reproduction, and many other physiological processes in humans and other species. The principal estrogens in humans are estradiol (E2), estrone (E1), and estriol (E3), with estradiol being the most active in reproductive tissues. In premenopausal individuals, estradiol is the dominant circulating estrogen; during pregnancy, the placenta contributes substantial amounts of estrogens; adipose tissue also produces estrogen via aromatase, especially after menopause.

Estrogen production is governed by the hypothalamic–pituitary–gonadal axis. The hypothalamus releases gonadotropin-releasing hormone, prompting the pituitary to secrete follicle-stimulating hormone and luteinizing hormone. FSH stimulates ovarian follicle development and estrogen synthesis, while feedback from estrogen helps regulate further secretion. In males and other tissues, smaller amounts of estrogen are produced by the testes and peripheral conversion of androgens.

Estrogen exerts its effects mainly through estrogen receptors ERα and ERβ, which function as transcription factors and regulate gene expression in target cells. Non-genomic signaling also occurs at the cell membrane. Estrogen influences a wide range of tissues, including the uterus and vagina, breasts, bones, brain, liver, and cardiovascular system.

Biological roles include the initiation of puberty, maintenance of female secondary sexual characteristics, regulation of the menstrual cycle, and preservation of bone mineral density. Estrogen levels and activity can be altered by age, pregnancy, health status, and medications.

Clinical aspects focus on estrogen deficiency and replacement therapy, contraception, and gender-affirming care. Hormone therapies are individualized due to risks such as venous thromboembolism, certain cancers, and cardiovascular effects.