The Link Between Testosterone and Estrogen
Testosterone and estrogen are typically considered to be hormones unique to each sex. In reality, men and women manufacture and secrete both. It is the difference in concentrations of the hormones that result in the sexual characteristics specific to each sex. If the balance between the two hormones shifts, it can cause medical conditions such as polycystic ovarian syndrome, gynecomastia (breast development in men) and erectile dysfunction.
What is a Testosterone and Estrogen?
Testosterone is an anabolic steroid and the primary male sex hormone. It is made in the body from cholesterol. Men secrete it from the testicles and women secrete it from the ovaries.
Estrogen is produced primarily by the ovaries, but during pregnancy, it is also produced by the placenta. Estrogen promotes the development of secondary sexual characteristics in women, such as breast development and fat distribution.
Testosterone promotes muscle and bone growth and development, helps prevent osteoporosis and affects the growth of body hair. Estrogen is not one substance but several substances collectively known by that term. These are estrone, estradiol and estriol, with estradiol being the most potent. In addition, women produce an estrogen called estetrol during pregnancy. Both men and women have lower levels of estrogen than testosterone in the circulation. Both of these hormones affect the libido.
Testosterone and Estrogen Differences
Estrogen and testosterone share similarities as well as differences. Both are hormones – substances produced by the body that make other tissues, organs and cells grow and function. Both affect sexual characteristics and bone growth and development. Either may affect the libido and mood in an individual. Both hormones are present in men and women, but in differing amounts. Both are used as medications when blood levels are low as a result of aging, injury or disease. However, testosterone has a much more significant effect on sexual function in males than estrogen does in women. Both hormones also have a significant effect on fertility in women, but not so much in men. Testosterone promotes muscle development and growth, while estrogen promotes fat distribution. Estrogen is produced not only in the sexual organs but in fat cells and adrenal glands.
Testosterone and Estrogen Levels
Men produce about 20 times more testosterone each day than women do. They also metabolize it more quickly. The level of testosterone in a healthy male is seven to eight times that of a healthy female. The normal level of testosterone in the blood ranges between 270 to 1070 ng/dL in men. The average level is around 679 ng/dL. In women testosterone levels range from 15 to 70 ng/dL. Although estrogen has different components, the one most commonly measured is estradiol. The normal level of estradiol in men (which is measured in picograms) is 20 to 55 pg/mL or 10 to 40 pg/mL, depending on the type of test used. In women, a normal estradiol level can range from 40 to 50 pg/mL. However, estradiol levels vary widely during the menstrual cycle and at other times in a woman's life. The level might be as high as 400pg/mL at ovulation. Estradiol levels can be up to 100 times the “normal” levels when a women is pregnant. After menopause, estradiol levels usually drop as low as 10 to 20 pg/dL.
When testosterone levels are too high in women, they may develop the following conditions:
- Frontal or male-pattern balding
- An enlarged clitoris
- Increased muscle mass
- A deeper voice than is usual in women
- Changes in libido or mood
- Polycystic ovarian syndrome, characterized by obesity, menstrual irregularities, excessive facial hair and infertility.
When estrogen levels are too high in men, they may develop:
- An increased risk of cancer and heart disease
- Gynecomastia, or enlarged breasts
- Loss of muscle mass
- Changes in libido or mood.
A Balancing Act
Perhaps the most important thing to understand about the link between these two sex hormones is that they are not independent of one another. They interact in the body and must remain in balance for best health. As women age, it is normal for estrogen levels to drop during menopause. Men do undergo a similar change, but their testosterone levels gradually decrease as they age. In some cases, these changes happen at a younger age than is usually expected and can cause physical changes and emotional distress. Although menopause is a natural process, some women suffer from severe night sweats, mood swings or other problems that disrupt their lives. Men may have difficulty with sexual functioning. Medications can be helpful for those individuals.
Hormone levels can be measured with blood tests, although doctors also take a patient's symptoms into account before deciding to prescribe testosterone or estrogen. Estrogen is available as injections, in oral forms and in creams or patches. Testosterone is usually given by injection. Both require a prescription.