Thyroid
Free Thyroxine Index
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Thyroid
T3.reverse
Reverse T3 is the brake pedal of your thyroid system. Instead of activating your metabolism like Free T3, rT3 blocks it. Your body makes more reverse T3 when you're stressed, inflamed, sick, or under-eating — it's a survival move that slows everything down. High rT3 with normal TSH and Free T4 often means you’re converting thyroid hormone inefficiently, leading to fatigue, brain fog, or weight plateaus even when other labs look "fine."
- Unit
- pg/mL
- Health impacts
- Metabolic Health · Energy · Thyroid · Brian Fog
In your dashboard
Your trend, against your optimal range.
Example data · how your trend would appear once you test
At every level
What we'd do at any value.
Exploring
16.6pg/mL
LowOptimal 9.2–24.1High
In your optimal zone
Habits that hold this position.
No specific guidance for this zone yet. We're working on it and will update this soon.
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