What is total testosterone?

Total testosterone is a blood test that measures the sum of all testosterone circulating in your system. This includes testosterone bound to sex hormone-binding globulin (SHBG) and albumin, plus a small amount of unbound testosterone. It is the standard initial test ordered when evaluating testosterone levels and is typically reported in nanograms per deciliter (ng/dL).

Most labs reference an adult male range of 300 to 1000 ng/dL as normal, though this varies by lab and testing methodology. Results below 300 ng/dL are often flagged as low testosterone, a condition called hypogonadism. However, total testosterone alone does not tell the full picture of testosterone availability to cells.

The difference between total and free testosterone matters clinically. Free testosterone is the unbound hormone that actually acts on tissue receptors. A man can have a total testosterone level within normal range yet still experience low free testosterone if he has high SHBG levels (which bind up the hormone). Conversely, someone with a lower total level may have sufficient free testosterone if SHBG is low. Many TRT providers in Florida order both total and free testosterone tests, along with SHBG, to get a complete picture before making treatment decisions. Total testosterone remains the screening test of choice because it is less expensive and more stable than free testosterone measurement.