Women and men both produce a range of sex hormones. While hormones like estrogen and progesterone are most important for female reproductive function, women also produce testosterone, which contributes to fertility and other body functions. The amount of testosterone normally in a woman's body varies, primarily depending on age, menstrual status and pregnancy. Certain medical conditions can also affect a woman's testosterone level.
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In women of childbearing age, roughly 25 percent of circulating testosterone comes from the ovaries, 25 percent comes from the adrenal glands, and the remaining 50 percent arises from conversion of testosterone precursors in other body sites. Although the role of testosterone in women is not as well understood as it is in men, the hormone is known to affect ovarian function, bone strength, and is believed to contribute to sexual desire (libido).
Circulating testosterone exists in a biologically-active free form and a bound form that is inactive. Depending on what test(s) your doctor orders, the laboratory will report the free testosterone level, the total testosterone level (free plus bound forms), or both. According to Mayo Medical Laboratories, the normal range for total testosterone in women is 8 to 60 nanograms per deciliter (ng/dL). The range for free testosterone gradually decreases as a woman ages. Examples for specific age ranges from Mayo Medical Laboratories include:
- 20 to less than 25 years: 0.06 to 1.08 ng/dL
- 30 to less than 35 years: 0.06 to 1.03 ng/dL
- 40 to less than 45 years: 0.06 to 0.98 ng/dL
- 50 to less than 55 years: 0.06 to 0.92 ng/dL
- 60 to less than 65 years: 0.06 to 0.87 ng/dL
- 70 to less than 75 years: 0.06 to 0.82 ng/dL
Factors Affecting Testosterone in Women
Several factors can affect your testosterone level. Your age is especially influential. Your total testosterone level is usually highest in your early 20s and gradually declines as you age, although there is not a precipitous drop that accompanies menopause. Testosterone levels also vary with your menstrual cycle, being lowest during your period and peaking at mid-cycle. Additionally, testosterone levels tend to be lower in the early morning than later in the day.
Carrying excess body weight tends to increase your testosterone level, as does using hormonal contraceptives or hormone replacement therapy. Smoking may increase your testosterone level, although research on this association has yielded inconsistent results. Testosterone levels naturally increase during pregnancy but return to a normal level after delivery. Women who have had their ovaries removed have lower testosterone levels than those who have still their ovaries, even after menopause.
Causes of Abnormal Results
Several conditions can lead to an abnormal testosterone level in women. Polycystic ovary syndrome (PCOS) is the most common cause. This condition is associated with excess testosterone and related hormones known collectively as androgens. Other possible causes of elevated testosterone in women include adrenal, ovarian, and pituitary tumors. Low testosterone levels occur with ovarian failure, also known as primary ovarian insufficiency.
Signs and Symptoms
Excess testosterone in a woman can cause a variety of symptoms that often differ in severity, depending on the underlying cause. Common examples include:
- Increased acne
- Increased body and/or facial hair
- Thinning scalp hair
- Weight gain
- Irregular periods
A low testosterone level can also interfere with normal ovarian function and cause menstrual irregularity. However, other signs and symptoms associated with a low testosterone level in women are less well defined, largely because there is no specific level clearly associated with the development of symptoms. Symptoms purported to be associated with low testosterone levels in women include:
- Decreased sex drive
- Loss of muscle mass or strength
- Depressed mood
If you are concerned about your testosterone level, talk with your doctor.
Reviewed and revised by: Tina M. St. John, M.D.