What is testosterone?

Testosterone is the "male" sex hormone made in men primarily in the testes. It stimulates the development of male sex characteristics such as the low voice, growth of the penis, body hair and muscle development. It also stimulates the desire for sex and provides firm bones.

Testosterone is also made in the adrenal glands (in both men and women) and in small amounts in the ovaries (in women). In women, much testosterone is converted to estradiol, the "female" sex hormone.

Testosterone is approximately 95% bound to the proteins albumin and SHBG (sex hormone binding globulin). Only free testosterone is active.

When is this test done?

• In babies where it is difficult to tell immediately after birth whether it is a boy or a girl.
• In girls and women who have male characteristics, such as excessive hair or a low voice.
• In women who cannot conceive.
• In boys who reach puberty too early or too late.
• In men whose wives can't conceive.
• In men with osteoporosis.
• In men who have small testicles and / or little libido