What is total testosterone?

Total testosterone is the standard blood test that measures every form of testosterone present in your bloodstream. This includes testosterone bound to sex hormone-binding globulin (SHBG) and albumin, as well as a small amount of free testosterone that circulates unbound. Most laboratories report total testosterone in nanograms per deciliter (ng/dL), with reference ranges typically between 300 and 1000 ng/dL for adult men, though this varies by lab and testing method.

Clinics use total testosterone as a primary screening tool because it is straightforward to measure and gives an overall picture of hormone production. However, total testosterone alone does not reveal how much testosterone is biologically available for your body to use. This distinction matters when evaluating whether symptoms like fatigue, low mood, or reduced muscle mass are connected to testosterone deficiency.

Free testosterone, by contrast, represents only the unbound fraction (usually 1-3% of total) and reflects the hormone your tissues can actively use. A patient might have a normal total testosterone level but low free testosterone if too much is bound to SHBG, or vice versa. TRT providers typically order total testosterone first and may follow with free testosterone testing or calculated free testosterone to make informed dosing decisions for hormone replacement therapy.