Free T3/Reverse T3 Ratio
Formula
FT3 / rT3What It Reveals
Thyroid hormone conversion efficiency.
Interpretation Ranges
Optimal
> 0.2 (when FT3 in pg/mL and rT3 in ng/dL)
Good T4-to-T3 conversion
Borderline
0.15–0.2
Suboptimal conversion — possible stress or illness
High Risk
< 0.15
Poor conversion — chronic illness, stress, or selenium deficiency
Clinical Significance
This ratio reveals whether the body is preferentially converting T4 into active T3 or inactive rT3. Low ratios explain hypothyroid symptoms with "normal" TSH.
What To Do
Reduce stress. Ensure adequate selenium (Brazil nuts). Treat underlying illness. Avoid extreme caloric restriction.
Component Biomarkers
GATOR Calculates This Automatically
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Source: Thyroid 2014
This content is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider for interpretation of your results.