Free Testosterone
Here’s what it reflects — and what to do about it.
Longetic pulls together every lab and record you’ve had, follows how Free Testosterone changes over time, and explains what’s shifting — so you walk into your next appointment prepared, with reminders for retests along the way.
What is Free Testosterone?
The small fraction of testosterone circulating unbound to proteins, so it is freely available for your body to use.
Most testosterone in your blood is attached to proteins like SHBG and albumin; free testosterone is the portion that is not bound and can act on your tissues. Because total testosterone can look normal even when the active free portion is off, this test can help clarify symptoms. In men, lower free testosterone can be associated with low sex drive, fatigue, or reduced muscle and bone strength; in women, higher levels can be associated with conditions such as PCOS. Results are interpreted differently by sex and age, and a single value is not a diagnosis.
What to know about Free Testosterone
Understanding Free Testosterone means knowing what it reflects, what tends to move it, and the signs that suggest it’s worth a closer look — so you can bring the right questions to your next appointment.
This glossary entry is for informational purposes only and is not a substitute for professional medical advice. Read our Medical Disclaimer.
References
About our sources
Official sources
Government health agencies, national institutes, and intergovernmental bodies whose guidelines carry regulatory or policy weight.
Clinical / professional
Medical societies, specialty colleges, and professional associations whose consensus statements reflect clinical practice standards.
Peer-reviewed research
Original research articles and systematic reviews published in indexed journals and verified through PubMed or DOI.