TESTOSTERONE TOTAL
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. (See the "What is being tested?" section for more.)The testosterone test may be used to help evaluate conditions such as:Delayed or precocious (early) puberty in boysDecreased sex drive in men and womenErectile dysfunction in menInfertility in men and womenTesticular tumors in menHypothalamus or pituitary disordersHirsutism and virilization in girls and womenTypically, a test for total testosterone is used for diagnosis. The total testosterone test measures testosterone that is bound to proteins in the blood (e.g., albumin and sex-hormone binding globulin [SHBG]) as well as testosterone that is not bound (free testosterone).About two-thirds of testosterone circulates in the blood bound to SHBG and slightly less than onethird bound to albumin. A small percent (less than 4%) circulates as free testosterone. Free testosterone plus the testosterone bound to albumin is the bioavailable testosterone, which can act on target tissues.
