What is an optimal Free T3 level?
The short answer
Optimal Free T3 is above 3 pg/mL, as stated on video.
Most labs call Free T3 low only under 2.3. So your report can come back normal at 2.7 while you sit under the optimal floor.
“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”
What each range means
- under 2.3 pg/mL Most labs flag this as low
- 2.3–3 pg/mL Normal on most reports. Below optimal Dr. Peter Attia · 7:42 →
- above 3 pg/mL Optimal
What Free T3 measures
The active thyroid hormone that is unbound and available to your tissues.
The active form does the work in cells. So it can show a problem while the signaling hormone still looks fine.
Checked against MedlinePlus — Triiodothyronine (T3) Tests.
Why it matters, on the record
“if you have um a good T3 level your your cholesterol is in check your memory is good your your metabolism is good you stay thin it helps your hair grow and helps your muscles um prevents muscle aches constipation”
Common questions
What is an optimal Free T3 level?
Above 3 pg/mL, from a quote on video (Dr. Peter Attia, 7:42).
What is a normal Free T3 level?
Most US labs print 2.3–4.2 pg/mL. Your report grades you against that range. It exists to catch disease, not to describe your best.
What does your Free T3 number mean?
On a typical lab range, under 2.3 pg/mL is low, 2.3 to 4.2 is normal and over 4.2 is high. Your own report prints its range next to your number, and that is the one your lab uses. The optimal range on this page comes with the quote behind it.
Is Free T3 of 2.7 normal?
A typical lab range calls it normal. On video, the optimal floor is 3 pg/mL (Dr. Peter Attia, 7:42), so by that line it is low.
What does the Free T3 test measure?
The active thyroid hormone that is unbound and available to your tissues. The active form does the work in cells. So it can show a problem while the signaling hormone still looks fine.