While testosterone is commonly referred to as the "male hormone," it's produced naturally by both males and females throughout their lifespan. Normal testosterone levels ensure that the brain, muscles, heart, blood vessels and bones develop and work properly. Testosterone also determines which sex-related characteristics a person develops, including external genitalia, patterns of body hair, voice quality and the fat distribution that creates gender-appropriate body shapes.
Control Center
The pituitary gland in both males and females regulates the production of testosterone. The pituitary continually monitors the amount of testosterone in the bloodstream and releases a hormone called luteinizing hormone, or LH, when those levels are too low.
Where It Comes From
The luteinizing hormone travels through the bloodstream to the adrenal glands, triggering the production of testosterone in boys, girls, men and women. LH also stimulates testosterone production in the testicles for males and the ovaries for women. As testosterone levels rise, the pituitary continues to monitor and regulate the production of the hormone.
Normal Levels
Throughout the lifespan, testosterone levels are lower in females than in males. Baby girls have about one-third the amount of testosterone that infant boys do, for example. Female testosterone levels are highest during the teen and early adult years, dropping significantly with the onset of menopause. Somewhere around 13 years of age, boys experience a surge in testosterone that triggers the onset of puberty, according to the University of Michigan Health System. After the age of 30, male testosterone levels decrease about 1 percent per year.
Indications
For a person who has symptoms that suggest his testosterone level is too high or too low, his doctor may send him to a medical laboratory for a blood testosterone level test. These symptoms include delayed or early puberty in boys, as well as excess body hair, deep voice, menstrual irregularities or infertility in females.
Expert Insight
A doctor may discuss testosterone replacement therapy if the patient's body does not produce a normal amount of testosterone. However, the National Institute on Aging studied the desired and the adverse effects of testosterone supplements and recommends, "Except for a relatively few younger and older men with extreme deficiencies, testosterone treatment is not deemed appropriate for most men at this time." And while testosterone therapy can improve sex drive or overcome sexual dysfunction in post-menopausal women, MayoClinic.com states, "The long-term safety of testosterone therapy for women is unknown."
