Testosterone is commonly known as a male steroid hormone (androgen), but it is present in both men’s and women’s bodies. In men, testosterone is produced mainly by the testicles, and in women, it is produced by the ovaries. In both sexes, small amounts of this hormone are also secreted by the adrenal glands. In males, testosterone secretion occurs before birth and shortly after birth; then it is almost nonexistent during childhood. It resumes and peaks at puberty, continues through adulthood, and declines during aging. On average, the circulating concentrations of testosterone of adult men are approximately 10 times higher than those of women. However, the distributions of testosterone concentrations in men and women are partially overlapping, so that there are men and women with similar ...