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In humans and most other vertebrates, testosterone is secreted primarily by the testicles of males and, to a lesser extent, the ovaries of females. It exerts its action through binding to and activation of the androgen receptor. It is biosynthesized in several steps from cholesterol and is converted in the liver to inactive metabolites. Testosterone is a steroid from the androstane class containing a ketone and a hydroxyl group at positions three and seventeen respectively. Insufficient levels of testosterone in men may lead to abnormalities including frailty, accumulation of adipose fat tissue within the body, anxiety and depression, sexual performance issues, and bone loss.Įxcessive levels of testosterone in men may be associated with hyperandrogenism, higher risk of heart failure, increased mortality in men with prostate cancer, male pattern baldness, criminality, impulsivity, and hypersexuality.
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In addition, testosterone in both sexes is involved in health and well-being, where it has a significant effect on overall mood, cognition, social and sexual behaviour, metabolism and energy output, the cardiovascular system, and in the prevention of osteoporosis. It is associated with increased sex drive, the inclination to impress partners and other courting behaviors. In 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. Testosterone is the primary male sex hormone and anabolic steroid in males.
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