What is total testosterone?

Total testosterone represents the complete amount of testosterone present in blood serum, measured in nanograms per deciliter (ng/dL). This lab value includes three forms: testosterone bound to sex hormone-binding globulin (SHBG), testosterone attached to albumin, and free testosterone circulating unbound. Most labs report total testosterone as the primary screening measure because it is straightforward to analyze and provides an overall picture of testosterone levels.

The distinction between total and free testosterone matters clinically. Free testosterone, typically just 1-3% of total testosterone, represents the portion available for immediate biological action at receptor sites. A person may have normal total testosterone but low free testosterone if SHBG levels are elevated, or vice versa. This is why hormone therapy clinics often order both measurements when evaluating candidates for treatment.

Reference ranges for total testosterone vary by lab and population, but adult males typically fall between 300-1000 ng/dL, while adult females range from 15-70 ng/dL. Results below or above these ranges may indicate hypogonadism, aging effects, or other hormonal conditions. Understanding your total testosterone level is the starting point for any hormone therapy assessment.