Testosterone, Total and Free (Men)
Total testosterone measures bound + unbound hormone; free testosterone is the bioactive fraction. Symptoms of low T correlate better with free T than with total — order both, and always draw blood at 7–10 a.m.
Total testosterone measures bound and unbound hormone in a single draw; free testosterone is the bioactive fraction that enters cells and drives the effects most associated with the hormone. Symptoms of low T — fatigue, libido drop, mood change, muscle loss, body-fat gain — correlate better with free T than with total, which means ordering both matters.
The biomarker
- Name: Testosterone — Total + Free (Men)
- Units: Total in ng/dL; Free in pg/mL
- Standard reference range: Total 264–916 ng/dL; Free varies by lab methodology
- Optimal range: Total 500–900 ng/dL; Free 15–25 pg/mL (under age 50)
- Draw time: 7–10 a.m. — testosterone peaks in the morning; late-afternoon draws understate true level
How to read your result
| Result | Interpretation |
|---|---|
| Total ≥ 500 + Free ≥ 15 | Adequate |
| Total 300–500 | Borderline — investigate lifestyle and sleep first |
| Total < 300 | Hypogonadism range — see clinician |
| Normal total + low free | High SHBG — order SHBG alongside |
What moves the needle
- Sleep. 7–9 hours of consistent, high-quality sleep is the most impactful lifestyle lever; testosterone is synthesised primarily during deep sleep.
- Body composition. Excess body fat aromatises testosterone to estrogen via adipose aromatase; reducing fat stores raises free T without any supplementation.
- Strength training. Heavy compound work (squat, deadlift, press) 3x/week is the exercise stimulus with the strongest documented androgenic response.
- Clinician referral. If symptomatic and confirmed low on two separate morning draws, an endocrinology referral is appropriate — do not interpret a single draw in isolation.
Why this test is worth asking for
- The standard reference floor (264 ng/dL) is a statistical artefact of a broad population including men with documented hypogonadism; most practitioners consider optimal to begin at 500 ng/dL.
- Symptoms often appear while total testosterone is still in the "normal" range, because SHBG rises with age and binds more hormone, reducing the free fraction. Free T reveals this when total looks acceptable.
- Draw time matters: a 3 p.m. blood draw can produce a value 25–40% lower than a 7 a.m. draw from the same individual on the same day — always draw in the morning.
Related protocols
- Zinc — Immune + Hormone Cofactor
- TSH, Free T3 and T4 — Thyroid Panel
- SHBG — Sex Hormone Binding Globulin
Sources
AgeGen lab guides are educational only. We do not provide medical diagnosis, prescribe brands, or recommend specific doses. Talk to a licensed clinician before changing your supplement or medication routine.
