How does estrogen contribute to the development of gynecomastia?

Updated: Mar 22, 2018
  • Author: George Ansstas, MD; Chief Editor: George T Griffing, MD  more...
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Estrogen production in males results mainly from the peripheral conversion of androgens (testosterone and androstenedione) to estradiol and estrone, which occurs through the action of the enzyme aromatase (mainly in muscle, skin, and adipose tissue). The testes secrete only 6-10 mg of estradiol and 2.5 mg of estrone per day. Since this only comprises a small fraction of estrogens in circulation (ie, 15% of estradiol and 5% of estrone), the remainder of estrogen in males is derived from the extraglandular aromatization of testosterone and androstenedione to estradiol and estrone. Thus, any cause of estrogen excess from overproduction to peripheral aromatization of androgens can initiate the cascade to breast development.

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