Testosterone is a steroid hormone produced by the male testes and the adrenal glands in both men and women. This hormone production is stimulated and controlled by the luteinizing hormone. Testosterone is seen in large amounts in boys during puberty, causing growth of body hair and muscle development. It also regulates the male sex drive and maintain muscle mass. It is found in small amount in females from the ovary. Testosterone test is used to diagnosed various conditions such as erectile dysfunction and infertility in men.