Testosterone functions as the principal male sex hormone. However, men and women produce varying levels of testosterone. Men secrete greater levels of testosterone throughout almost all stages of life than women, which explains the differences between men and women, according to "Goodman and Gilman's the Pharmacological Basis of Therapeutics." Testosterone regulates multiple body functions including growth and development, control of metabolic pathways, and the use and storage of energy, according to the Centers for Disease Control and Prevention.
Testosterone Levels Throughout Stages of Life
The body begins secreting testosterone at the time of conception. Testosterone levels peak during adolescence and early adulthood, according to the Mayo Clinic. The Mayo Clinic also reports that testosterone levels gradually decline with age, commonly about 1 percent a year after age 30.
Testosterone Levels in Fetal Development and Infancy
During the first trimester of pregnancy, the fetal testes begin secreting testosterone. High levels of testosterone stimulate the development of a male, while lower levels produce a female, according to "Goodman and Gilman's the Pharmacological Basis of Therapeutics." Shortly after birth, testosterone levels fall and then peak again around 2 to 3 months. At 6 months of age, testosterone levels fall again and remain at that level until puberty, as reported by Goodman and Gilman.
Testosterone Levels in Puberty
Puberty generally begins around age 12 in males. The increase in testosterone stimulates the development of mature sex organs along with an increase in muscle mass and muscle strength, according to Goodman and Gilman. Males also experience a growth sport and an increase in body weight. Goodman and Gilman also report that the skin becomes coarser; hair begins to grow on the legs and under the arms; and the voice becomes lower.
Testosterone Levels in Adulthood: Men
Testosterone maintains multiple body functions in adult males. According to the Mayo Clinic, testosterone maintains bone density, fat distribution, muscle strength and mass, red blood cell production, sex drive and sperm production. As a man ages, testosterone levels gradually decline. The decline in testosterone contributes to changes that generally occur as a man ages, including a decrease in energy, libido, muscle mass and strength, and bone mineral density, according to Goodman and Gilman.
Testosterone Levels in Adulthood: Women
The ovaries produce testosterone, which is the precursor to estrogen, or the female sex hormone. Goodman and Gilman report that testosterone functions as one of the principal hormones in the female body. Although testosterone generally has a greater effect on men, it also functions to maintain energy, libido, bone density, and muscle strength and mass in women. The Mayo Clinic reports that testosterone effectively boosts a woman's sex drive.
References
- "Goodman & Gilman's The Pharmacological Basis of Therapeutics, online edition, chapter 58"; Laurence L. Brunton, editor-in-chief and Associate Editors: Keith L. Parker, Nelda Murri, Donald K. Blumenthal, and Björn C. Knollmann; 2010.
- Centers for Disease Control and Prevention: Hormone Standardization
- MayoClinic: Testosterone Therapy: Key to Male Vitality?
- MayoClinic: Testerone Therapy in Women: Does it boost sex drive?
