What is an optimal Reverse T3 level?
The short answer
An optimal Reverse T3 level is under 12 ng/dL. That is Dr. Peter Attia's number. You can watch him say it below.
Most labs call Reverse T3 high only above 25. So your report can call 19 normal while it sits above where he draws the line.
“if someone's TSH is between about 0.5 and 2.0 and they're free t3 is above 3.0 and their reverse t3 is below 12 I find it very hard to see how they could have hypothyroidism regardless of the symptoms they have”
Where a number lands, and who said so
- under 12 ng/dL The range Dr. Peter Attia draws
- 12–25 ng/dL Normal on most reports. Above optimal“if someone's TSH is between about 0.5 and 2.0 and they're free t3 is above 3.0 and their reverse t3 is below 12 I find it very hard to see how they could have…” Dr. Peter Attia · 7:42 →
- over 25 ng/dL Most labs flag this as high
What Reverse T3 measures
An inactive form of thyroid hormone your body makes instead of the active one.
Your body makes more of it during illness, starvation and stress. It reads as a sign the body is throttling thyroid activity.
One of the doctors we cite, on why it matters
“the amazing thing is that whereas T3 is a super active molecule, reverse T3 is dead. It it has less activity than T4 even.”
Common questions
What is an optimal Reverse T3 level?
Under 12 ng/dL, according to Dr. Peter Attia.
What is a normal Reverse T3 level?
Most US labs print 8–25 ng/dL. Your report grades you against that range. It exists to catch disease, not to describe your best.
What does your Reverse T3 number mean?
Under 8 ng/dL, your report marks it low. Between 8 and 25 it prints as normal. Over 25, your report marks it high. Where the people we follow draw their own line is above.
Is Reverse T3 of 19 normal?
Your lab will call it normal. Dr. Peter Attia puts the ceiling at 12 ng/dL, so by that number it is high.
What does the Reverse T3 test measure?
An inactive form of thyroid hormone your body makes instead of the active one. Your body makes more of it during illness, starvation and stress. It reads as a sign the body is throttling thyroid activity.
Where does this number come from?
Dr. Peter Attia, on video. The link above jumps straight to that minute.