Bioavailable Testosterone
Hormones marker
Bioavailable Testosterone
Testosterone that is free or loosely bound to albumin. Represents the portion available to tissues (free T + albumin-bound T).
PED Notes
Bioavailable testosterone includes both free testosterone and albumin-bound testosterone (which can readily dissociate). It excludes only SHBG-bound testosterone. This is a more comprehensive measure of 'usable' testosterone than free T alone. Common on US lab panels (Quest, LabCorp) where it's reported in ng/dL. On AAS/TRT, bioavailable T will be elevated proportionally to total T, modified by SHBG status.
When high
Understanding Bioavailable T:
- Bioavailable T = Free T + Albumin-bound T (approximately 30-50% of total T)
- SHBG-bound T is NOT bioavailable (tightly bound, does not dissociate at tissues)
- More clinically useful than total T when SHBG is abnormal
If elevated (on cycle/TRT):
- Expected -- no intervention needed unless experiencing side effects
- Monitor androgenic side effects (acne, hair loss, prostate symptoms)
Whether pushing the dose higher actually adds more muscle, and where the returns collapse: Does more testosterone build more muscle?.
When low
Understanding Bioavailable T:
- Bioavailable T = Free T + Albumin-bound T (approximately 30-50% of total T)
- SHBG-bound T is NOT bioavailable (tightly bound, does not dissociate at tissues)
- More clinically useful than total T when SHBG is abnormal
If low (off-cycle):
- Check total T, free T, and SHBG to understand the cause
- High SHBG will lower bioavailable T even with normal total T
- See Free Testosterone and SHBG management protocols
Supplements & Lifestyle:
- Same protocols as Free Testosterone
- Boron (10mg/day) can lower SHBG and increase bioavailable fraction
Mood, anxiety and motivation are usually the first things people notice, and the first things they expect replacement to fix: TRT and mental health: anxiety, depression and the first 90 days.
Educational information, not medical advice. Nothing here is a prescription or a treatment plan, and it does not account for your history, medications or conditions. Use it to ask better questions: bring it to your doctor and decide together. Full disclaimer.
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range
VitalMetrics Range