Order T3 (tri-iodothyronine) blood testing online

In the majority of US states you can order free-T3 testing online and have the blood drawn at a local blood draw center (see my general overview of the process).

The most commonly-suggested measure of T3 is free T3. See the next section if you want total T3.

I'd suggest ordering from Life Extension because they have the cheapest price I know of ($31), and I've been happy with their service. You can also compare the other 5 free-T3 test providers I've found.

Take a look at my state-specific issues page if you're in AZ, MD, NJ, NY or RI.

Testing for total T3 instead of free T3

Smart-dude Ray Peat disagrees with the common view of what free-T3 testing indicates and suggests total-T3 testing instead. So here are the total-T3 providers I've found:

• Life Extension, $36.
• Walk-In Lab, $38.
• DirectLabs, $49.
• Personalabs, $50.
• Private MD Labs, $52.
• Health-Tests Direct:
  • When selecting LabCorp, $53.
  • When selecting Quest, $54.
• True Health Labs, $59.

Understanding the results

The American Association for Clinical Chemistry has helpful pages for understanding the test and answering common questions.