Testosterone

Testosterone is the primary male sex hormone and an anabolic steroid. In male-aligned humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.[3] In addition, testosterone is involved in health and well-being, and the prevention of osteoporosis. Insufficient levels of testosterone in people which primary sex hormone is testosterone may lead to abnormalities including frailty and bone loss.

Testosterone is a steroid from the androstane class containing a keto and hydroxyl groups at the three and seventeen positions respectively. It is biosynthesized in several steps from cholesterol and is converted in the liver to inactive metabolites. It exerts its action through binding to and activation of the androgen receptor. In humans and most other vertebrates, testosterone is secreted primarily by the testicles of males and, to a lesser extent, the ovaries of females. On average, in adult cisgender men, levels of testosterone are about 7 to 8 times as great as in adult cisgender women.

In addition to its role as a naturally produced hormone, testosterone is used as a medication - For transgender individuals, it is used in Female-to-Male Hormone Replacement Therapy.