How to get your T4 tested

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:

Understanding the results

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

Body organ cartoon characters with YouTube play button

If you're interested in self-testing as I am, you might enjoy my explainer videos and my Facebook / Twitter.


Please leave a comment if you see a way to improve this page or if you have any questions. Keep in mind that I know little about the medical side of bloodwork, I just enjoy making sites with lists of things.

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