---
title: "Bioavailable & Free Testosterone (Equilibrium Dialysis) Optimal Range vs Lab Normal (2026 Clinical Decoder & Protocol) | Nutrition Research Labs"
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description: "Decode your Bioavailable & Free Testosterone (Equilibrium Dialysis) (Free Testosterone) blood test: Longevity Optimal Target (95–155 pg/mL) vs Standard Lab Normal (35–155 pg/mL), assay interference, and Grade-A clinical protocols."
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> **Canonical Source:** [https://nutritionresearchlabs.com/biomarkers/free-testosterone](https://nutritionresearchlabs.com/biomarkers/free-testosterone)
>
> *Decode your Bioavailable & Free Testosterone (Equilibrium Dialysis) (Free Testosterone) blood test: Longevity Optimal Target (95–155 pg/mL) vs Standard Lab Normal (35–155 pg/mL), assay interference, and Grade-A clinical protocols.*

## Reference Range Comparison (pg/mL)

- **Longevity & Metabolic Optimal Range:** 95 – 155 pg/mL
- **Standard Lab Reference Interval ("Normal"):** 35 – 155 pg/mL
- **Why Standard Lab Ranges Mislead Patients:** Many commercial labs use direct analog radioimmunoassays (tracers) that are notoriously inaccurate. Furthermore, reference ranges include frail elderly populations, labeling 40 pg/mL
- **Pre-Draw Supplement Assay Interference Warning:** Direct RIA analog methods have high cross-reactivity and coefficients of variation up to 40%. The equilibrium ultrafiltration or Vermeulen calculated method using Total Testosterone, SHBG, and Albumin is the clinical standard.

## Decode the Next Biomarker on Your Blood Panel

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