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Testosterone
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Common Questions
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1. If I have a low testosterone level, will taking supplemental testosterone help?
2. I am a woman, so why do I need a testosterone test?
3. Is the amount of body hair directly proportional to the amount of testosterone in my body?
4. What are free and bioavailable testosterone?
1. If I have a low testosterone level, will taking supplemental testosterone help?
Maybe. Testosterone supplements, either with patches or injections, can raise testosterone levels. They may help to relieve some symptoms and to prevent muscle and bone loss that occurs with aging in men. However, this has not been definitively proven, and there is concern that testosterone replacement therapy may increase the risk of developing prostate cancer. This is because cancers grow in response to androgens, such as testosterone. In addition, although men with erectile dysfunction may have low testosterone, in many cases testosterone administration does not improve the symptoms. Therefore, consult your doctor for a medical evaluation and consultation to determine if this is the right therapy for you.
2. I am a woman, so why do I need a testosterone test?
Women’s bodies also produce testosterone but in small amounts. It is needed for hormonal balance and to help women’s bodies to function normally. If your body is producing too much testosterone, however, you may have more body hair than average, have abnormal or no menstrual periods, or be infertile. A testosterone test can help your doctor to understand what is causing your symptoms.
3. Is the amount of body hair directly proportional to the amount of testosterone in my body?
Studies have shown a proportional relationship of testosterone levels to the amount of body hair. The hair growth response to testosterone differs in different parts of the body. Hence, in some men, for example, testosterone promotes hair growth in the abdomen and back while hair growth is suppressed in the scalp, leading to male pattern baldness. Genetics plays a major role in the expression of the 5 alpha reductase enzyme, which converts testosterone to the hair-altering compound dihydrotestosterone, leading to a family tendency towards balding. The drug finasteride (propecia) inhibits the action of 5 alpha reductase, and can reverse male pattern baldness in some men.
4. What are free and bioavailable testosterone?
Testosterone is present in the blood as "free" testosterone (2-3%) or bound testosterone. The latter may be bound to either albumin (a serum protein) or to a specific binding protein called Sex Steroid Binding Globulin (SSBG) or Sex Hormone Binding Globulin (SHBG). The binding of testosterone to albumin is not very tight and is easily reversed; so the term bioavailable testosterone (BAT) refers to the sum of free testosterone plus albumin-bound testosterone. Alternatively, it is the fraction of circulating testosterone that is not bound to SSBG. It is suggested that BAT represents the fraction of circulating testosterone that readily enters cells and better reflects the bioactivity of testosterone than does the simple measurement of serum total testosterone. Also, varying levels of SSBG can result in inaccurate measurements of BAT. Decreased SSBG levels can be seen in obesity, hypothyroidism, androgen use, and nephritic syndrome. Increased levels are seen in cirrhosis, hyperthyroidism, and estrogen use. In these situations, measurement of free testosterone may be more useful. However, technically, free testosterone is difficult to measure accurately.
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This article was last reviewed on
January 21, 2005.
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