Order T4 (thyroxine) blood testing online

In the majority of US states you can order free-T4 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 T4 is free T4. See the next section if you want total T4.

I'd suggest ordering from Life Extension because they have the cheapest price I know of ($28), and I've been happy with their service. You can also compare the other 6 free-T4 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 T4 instead of free T4

Smart-dude Ray Peat disagrees with the common view of what free-T4 testing indicates and suggests total-T4 testing instead. So here are the total-T4 providers I've found:

• Walk-In Lab, $26.
• Life Extension, $29.
• Private MD Labs, $32.
• Health-Tests Direct:
  • When selecting LabCorp, $34.
  • When selecting Quest, $48.
• Personalabs, $46.
• DirectLabs, $49.
• True Health Labs, $59.

Understanding the results

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