What is total testosterone?

Total testosterone is the sum of all testosterone in your blood, regardless of whether it is bound to proteins (sex hormone-binding globulin and albumin) or circulating freely. A single blood draw measures this combined level in nanograms per deciliter (ng/dL).

In clinical practice, total testosterone serves as the initial diagnostic marker because it accounts for the majority of circulating hormone and requires only one straightforward serum test. Reference ranges typically fall between 300-1000 ng/dL for adult men, though individual labs may vary slightly. Levels below 300 ng/dL often prompt further evaluation for testosterone deficiency.

Medical providers use total testosterone as the entry point for TRT screening because it is cost-effective, widely standardized, and available through most laboratory networks. When total testosterone comes back low, follow-up testing may include free testosterone and bioavailable testosterone to clarify how much hormone is actually available to body tissues. Time of testing matters too: testosterone levels are highest in the early morning, so clinicians typically order fasting draws between 7 and 10 a.m. for consistency.

Finding an experienced provider ensures your test is ordered correctly and results are interpreted in context with your symptoms and medical history.