Testosterone, Free is a measure of the amount of unbound testosterone in the blood that is available for use by the body. Low levels of free testosterone can cause symptoms such as decreased libido, erectile dysfunction, and decreased muscle mass in men.

iollo markers that associate with Testosterone, Free


Alanine is involved in protein and energy metabolism. Higher alanine levels may reflect increased muscle protein breakdown which could be associated with lower free testosterone.


Arginine is a precursor for nitric oxide which plays a role in vasodilation and blood flow. Reduced arginine and nitric oxide may be associated with erectile dysfunction and potentially lower free testosterone levels.