Androgens refer to a group of male hormones that play many crucial roles in the body. One important hormone that belongs to this group is testosterone. This male hormone is produced in the testes and regulated by the hypothalamus in the brain. There are three types of testosterone that are produced in the body, classified by what proteins are and aren’t attached to the basic steroid structure.
This is the purest form of testosterone. There are no proteins attached to the basic structure, hence, considered unbound or “free’’. They easily enter the cells and activate cellular receptors to stimulate various cellular processes that produce the benefits of testosterone. Free testosterone is the one that produces the most beneficial effects, but is also the smallest in amounts. It only accounts 2 to 3% of a man’s total testosterone levels. This is also the type of testosterone that should be increased.
This type comprises about 40 to 50% of a man’s total testosterone levels. The testosterone molecule binds with the sex-hormone-binding-globulin or SHBG, which is produced in the liver. This type regulates the free testosterone levels in the body. In itself, SHBG-bound Testosterone is biologically inactive, which means the body cannot use this type of testosterone. It can help neither build muscles nor boost the mood. In normal levels, SHBG-bound Testosterone is not bad, but too much of it is not desirable. Tests would reveal high testosterone levels but still suffer from deficiency symptoms. SHBG tends to bind itself to a lot of testosterone, leaving too few free Testosterone for the body to use.
Some testosterone binds with albumin, a protein produced in the liver that mainly functions for the stabilization of extra-cellular fluid volumes. This bound testosterone is also biologically inactive, which means the body cannot also use this form. The difference with SHBG-bound Testosterone is that the bond between albumin and testosterone is weak and can easily be destroyed in order to release the Testosterone and be available for the body to use.