Understanding Your Testosterone Levels

Receiving a testosterone lab report can be confusing. Reference ranges vary between laboratories, results are presented in different units, and the distinction between total and free testosterone is rarely explained. This article walks you through what each measurement means and how to interpret your results in a clinical context.

Total testosterone is the most commonly reported figure and represents the combined amount of testosterone in your bloodstream — both the portion bound to proteins (primarily SHBG and albumin) and the small fraction circulating freely. Normal reference ranges typically run from 300 to 1,000 ng/dL, though many labs use slightly different cutoffs and the "normal" range encompasses a very wide spectrum of biological experience.

Free testosterone is the biologically active fraction — the testosterone your cells can actually use. Because SHBG levels rise with age and certain health conditions, some men have total testosterone in the normal range but meaningfully low free testosterone. This is why we always measure both. Free testosterone below 50–70 pg/mL is generally considered suboptimal, though symptomatic thresholds are individual.

LH (luteinising hormone) and FSH (follicle-stimulating hormone) help determine whether low testosterone originates in the testes (primary hypogonadism) or in the hypothalamic-pituitary signalling pathway (secondary hypogonadism). This distinction matters because the underlying cause influences treatment options. Secondary hypogonadism in younger men, for example, may respond to clomiphene citrate rather than exogenous testosterone.

Haematocrit — the proportion of red blood cells in your blood — is monitored on TRT because testosterone stimulates red blood cell production. Elevated haematocrit increases blood viscosity and is a key safety marker. We target haematocrit below 52% and adjust dosing or recommend therapeutic phlebotomy if levels climb. Prostate-specific antigen (PSA) is also tracked, as TRT is contraindicated in men with untreated prostate cancer.