Serum testosterone refers to a measurement of testosterone. Specifically, serum testosterone indicates the total amount of testosterone circulating in the blood serum. While serum testosterone levels indicate how much testosterone you have in your body, it does not indicate how much testosterone is being utilized. The amount of active testosterone your body uses is measured by free testosterone. Free testosterone is the testosterone in the body that is not bound by Sex Hormone Binding Globulin (SHBG). Normally, approximately 2% of your serum testosterone is free testosterone. This tells us that the body will only utilize a small amount of the primary androgen.
In order to ensure we utilize as much testosterone as possible, we have a few options. By increasing serum testosterone levels with everything else in the body remaining the same, the 2% figure goes up. Weíre still utilizing a 2% total, but with serum testosterone levels now higher the 2% figure becomes higher. Another option is to lower or reduce SHBG. If we reduce SHBG this increases our free testosterone levels. This can be accomplished when Insulin Like Growth Factor-1 (IGF-1) levels increase, as well as when insulin levels increase. Decreasing estrogen levels will also decrease SHBG. While none of this actively promotes an increase in serum testosterone levels, it does give us more active testosterone to pull from.
There has been for years a long standing argument revolving around testosterone measurements. Some say the measurement of serum testosterone levels doesnít matter since free levels represent the only testosterone being used. However, assuming all other hormone levels are within a normal range, we know the individual is only utilizing approximately 2% of his testosterone, and by this the total serum level is often a fine measurement.
In the U.S. if total serum testosterone levels for a man fall below 300ng/dl this is normally considered a low level state. This will especially hold true if the measurement is taken in the morning. The morning represents the time of day when an individualís testosterone levels will be at their peak. While a free testosterone measurement is useful, we know if the average manís serum testosterone levels are below 300ng/dl his free levels will only represent approximately 2% of that number. The overall point, measuring serum testosterone levels is a fine indicator of a patients overall condition.
Serum testosterone levels can be increased, and this is normally done so by the use of exogenous testosterone. Exogenous testosterone is simply synthetic testosterone provided to the body in an effort to increase serum levels. There are several forms of exogenous testosterone to choose from, such as transdermal applications, subcutaneous implant pellets, injectable compounds and oral tablets. Each form has positive and negative traits, however, each is comprised of the same, identical testosterone hormone, and the same hormone your body naturally produces. In this case, it is merely a synthetic version that originated outside the body.