TESTOSTERONE

a steroid hormone produced by the testes and adrenal glands. Testosterone is required for sperm production, the development of the male reproductive organs, and the emergence of male secondary sexual characteristics. The hormone is also required for the buildup of lean muscle mass. Testosterone levels are often low in HIV positive men; the hormone is under study as a therapy for wasting syndrome. Possible side effects include acne, mood swings, change in sex drive, liver toxicity, prostate enlargement and masculinization in women.