Bioavailable Testosterone

Hormones marker

Bioavailable Testosterone

Category: Hormones
Unit: nmol/L

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)

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

History Chart

Reading History

Frequently Asked Questions

Reference Ranges

Standard Range

3.8 - 20 nmol/L

VitalMetrics Range

7 - 24 nmol/L

Statistics