What It Measures
The amount of testosterone not bound to SHBG or albumin, freely available to bind to androgen receptors.
Free testosterone is the unbound, bioavailable fraction (~2-3% of total). It is the active form that enters cells and exerts biological effects. Often more clinically relevant than total testosterone.
Current Value
What High Means
High free testosterone enhances muscle growth, libido, and energy. Excessively high levels (usually exogenous) may cause side effects.
Possible Symptoms
Similar to high total testosterone
What Low Means
Low free testosterone causes symptoms even when total testosterone is normal. This disconnect often occurs when SHBG is elevated (from aging, liver issues, or excess estrogen).
Possible Symptoms
Fatigue, low libido, ED, mood issues — even with normal total T
Risk Factors
Same as total testosterone when low; SHBG elevation masks adequate total T
Actionable Advice
Supplements
- •Boron (can reduce SHBG)
- •Magnesium
- •Zinc
- •Stinging nettle root (SHBG modulation)
Diet & Lifestyle
- •Address SHBG if elevated
- •Same lifestyle factors as total testosterone
- •Consider free T if total T is normal but symptoms persist
- •Resistance training increases free T acutely
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Historical Trend
Related Biomarkers
All Readings
| Date | Value | Change |
|---|---|---|
| 2026-01-28 | 238.1 pg/mL | 0.0 |
| 2025-08-25 | 238.1 pg/mL | — |