Testosterone testing is used to diagnose several conditions in men, women, girls, and boys. Testosterone is the main sex hormone in men, produced mainly by the testicles, and is responsible for male physical characteristics. Although it is considered to be a “male” sex hormone, it is present in the blood of both males and females.
Most testosterone in the bloodstream is bound to proteins SHBG (sex hormone binding globulin) and albumin. Around 4% is unbound and therefore available to the body’s tissues. It is possible to have raised total testosterone levels but still be symptomatic of low testosterone if your level of free testosterone is low.
Free testosterone is a measure of testosterone that is not bound to SHBG.
Although used predominantly by men to test for symptoms of low testosterone, the test can also be used to measure a woman’s testosterone levels when investigating polycystic ovarian syndrome (PCOS).
High free testosterone in men and women can have significant impacts on health and behavior. Testosterone is believed to play an important role in bone and muscle strength and libido in women