Testosterone is a naturally occurring hormone in both men and women. In women, testosterone is made in the ovaries and adrenal glands. Estrogen, which is a vital hormone for women, is made from testosterone. A woman's testosterone levels are highest in their early 20s. Testosterone is important in building muscle and plays a vital role in sports performance. Women can experience testosterone deficiency as they approach and enter menopause.

Normal testosterone levels in women vary from individual to individual. Testosterone levels, along with other female hormones, vary during a woman's menstrual cycle. Testosterone is at its highest level in the middle of the menstrual cycle as well as during ovulation. When women reach their 40s, testosterone levels may be reduced as much as 50 percent as compared to women in their 20s. Women can experience a sudden drop in testosterone by as much as 50 percent if they have their ovaries surgically removed. Such decreases in testosterone can lead to muscle wasting in women.

According to the "Journal of Applied Physiology," a pharmacological dose of testosterone increased muscle mass. It is suggested that this increase in muscle mass is a result of testosterone increasing muscle protein synthesis. Testosterone deficiency in women can lead to decreased energy, decreased sex drive and a decrease in strength and endurance. According to the American College of Sports Medicine, when individuals use testosterone -- an anabolic steroid -- they will experience increases in muscle and strength significantly beyond those acquired through training alone.

Anabolic steroids such as testosterone used by women can significantly increase lean muscle. Using testosterone can also lead to significant increases in strength, speed and endurance, thereby greatly enhancing an athlete's performance. Steroid use is illegal and violates state and federal laws. In order to maintain an even playing field, organizations that oversee sports from the National Federation of State High School Associations to the United States Olympic Committee oppose and ban the use of anabolic steroids.

Testosterone use by women can lead to a myriad of side effects such as deepening of the voice, male pattern baldness, menstrual cycle abnormalities, reduce breast size, increases in body hair and acne. It can also lead to mood changes and potential liver problems. Testosterone use by adolescent females can lead to a permanent halting of growth. The American College of Sports Medicine also reports that anabolic steroid use has been linked to heart disease, stroke and increased aggression.

According to the American College of sports medicine, female adolescent steroid use is between 0.5 and 2 percent. The ACSM reports that based on three national surveys, female adolescent steroid use has increased significantly since 1991. According to the 1995 Youth Risk and Behavior Surveillance System, 2.4 percent of female high school students have used anabolic steroids. This translates to approximately 175,000 female high school students. Other countries such as Sweden, England, South Africa and Canada have reported similar numbers of high school students using anabolic steroids.