Reverse T3
Reverse T3 is an inactive metabolite of T4 produced by alternative deiodination. Levels rise during severe illness, calorie restriction, trauma, and chronic stress and may reflect a shift away from active T3 production. High reverse T3 with low or normal free T3 is sometimes called euthyroid sick syndrome and usually resolves with recovery.
4 providers include this
Thyroid Function
9.2-24.1 ng/dL
What is Reverse T3?
Reverse T3 is an inactive metabolite of T4 produced by alternative deiodination. Levels rise during severe illness, calorie restriction, trauma, and chronic stress and may reflect a shift away from active T3 production. High reverse T3 with low or normal free T3 is sometimes called euthyroid sick syndrome and usually resolves with recovery.
Why It Matters
Elevated during stress, illness, or caloric restriction. High levels despite normal TSH/T4 may explain persistent fatigue and metabolic issues. Indicates thyroid hormone conversion problems.
Which Providers Test Reverse T3?
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 Reverse T3?
Reverse T3 is an inactive metabolite of T4 produced by alternative deiodination. Levels rise during severe illness, calorie restriction, trauma, and chronic stress and may reflect a shift away from active T3 production. High reverse T3 with low or normal free T3 is sometimes called euthyroid sick syndrome and usually resolves with recovery.
What is the optimal range for Reverse T3?
The standard reference range for Reverse T3 is 9.2-24.1 ng/dL. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include Reverse T3?
4 out of 22 blood testing providers include Reverse T3 in their panels. This biomarker has limited availability.
What category does Reverse T3 fall under?
Reverse T3 is categorized under Thyroid Function. This category includes biomarkers that help assess related aspects of health and wellness.
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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