Is four hours between taking thyroid medications and having thyroid tests done enough time?

This will depend if you take a T3 containing medication or not. If you’re just taking straight T4, like Synthroid, then the testing should be fine. But, if you’re doing a T3 containing medication within those 4 hours, that could potentially skew your test results. On the day that you test your thyroid, you may actually want to postpone until after you do the test.