T3 Uptake
T3 uptake is an indirect measure of how much thyroid hormone-binding protein is available to bind added labeled T3. It was historically combined with total T4 to calculate the free thyroxine index before direct free T4 assays became widely available. Results are affected by estrogen, pregnancy, and certain drugs, and the test is now used less often.
2 providers include this
Thyroid Function
24-39%
What is T3 Uptake?
T3 uptake is an indirect measure of how much thyroid hormone-binding protein is available to bind added labeled T3. It was historically combined with total T4 to calculate the free thyroxine index before direct free T4 assays became widely available. Results are affected by estrogen, pregnancy, and certain drugs, and the test is now used less often.
Why It Matters
Reflects binding protein availability. Used with total T4 to calculate free thyroxine index. Less commonly used with free hormone assays available.
Which Providers Test T3 Uptake?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | — | $349 | 65 |
 Labcorp OnDemand | — | $398 | 40+ |
| — | $486 | 40+ | |
| — | $449 | 288 | |
| — | $349 | 100+ | |
| — | $829 | 54 | |
 Function Health | — | $365 | 160+ |
| — | $250 | 65 | |
| — | $495 | 80+ | |
| — | $895 | 100+ | |
| — | $1950 | 130+ | |
| — | $375 | 95+ | |
| — | $Varies | 75+ | |
| — | $190 | 100+ | |
| — | $99 | 50 | |
| — | $124 | 60 | |
| — | $349 | 130+ | |
| — | $349 | 80+ | |
| — | $375 | 85 | |
| ✓ | $700 | 128 | |
| — | $99 | 100+ |
Frequently Asked Questions
What is T3 Uptake?
T3 uptake is an indirect measure of how much thyroid hormone-binding protein is available to bind added labeled T3. It was historically combined with total T4 to calculate the free thyroxine index before direct free T4 assays became widely available. Results are affected by estrogen, pregnancy, and certain drugs, and the test is now used less often.
What is the optimal range for T3 Uptake?
The standard reference range for T3 Uptake is 24-39%. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include T3 Uptake?
2 out of 22 blood testing providers include T3 Uptake in their panels. This biomarker has limited availability.
What category does T3 Uptake fall under?
T3 Uptake is categorized under Thyroid Function. This category includes biomarkers that help assess related aspects of health and wellness.
Want to improve this marker? YouBoost rates health interventions by evidence strength.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed:2026-04-12