Testosterone, Total and Free (Men)
Total testosterone measures bound and unbound hormone; free testosterone is the unbound fraction. Draw between 7 and 10 a.m., and confirm a low result on a second morning sample.
Total testosterone measures bound and unbound hormone in a single draw; free testosterone is the unbound fraction, which is more available for the body to use — and the sample should be taken between 7 and 10 a.m. Most testosterone is bound to proteins such as sex-hormone-binding globulin (SHBG) and albumin.
The biomarker
- Name: Testosterone — Total + Free (Men)
- Units: Total in ng/dL; Free in pg/mL
- Standard reference range: Total 264–916 ng/dL — the Endocrine Society's harmonized range for non-obese men aged 19–39; Free varies by lab methodology (ranges vary by lab)
- Draw time: between 7 and 10 a.m., per MedlinePlus
How to read your result
| Result | Interpretation |
|---|---|
| Within the lab's range | No testosterone question raised by this draw |
| Below the lab's range | Repeat on a second morning sample before it means anything |
| Normal total, question about active hormone | Ask whether SHBG should be measured — it shows how much testosterone is active |
| Consistently low + symptoms | A clinician's question — the Endocrine Society diagnoses hypogonadism only with symptoms and consistently low levels |
What to do with the result
- Timing. Draw between 7 and 10 a.m.
- Clinician. A low result is confirmed on a repeat morning fasting test before a clinician interprets it — do not interpret a single draw in isolation, and do not start testosterone without a clinician.
Why this test is worth asking for
- Total and free testosterone answer different questions: total counts all of it, free counts the fraction not bound to proteins.
- The Endocrine Society published a harmonized normal range so results from standardized assays can be compared across labs.
Related protocols
Sources
- MedlinePlus — Testosterone Levels Test
- Endocrine Society — Landmark Study Defines Normal Ranges for Testosterone Levels
- Endocrine Society — Testosterone Therapy for Hypogonadism Guideline
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.
