Free T 4 and Free T3 testing

[Barrister]

I will be seeing my doctor today and intend to ask about testing FT4 and FT3. When should I get these tested ( what time of day is best?) and should I leave taking thyroxine until after it's been tested on that day? Thanks for your input. Clemmie

[humanbean]

The best time for getting thyroid function tests done is first thing in the morning. This is the time when TSH is at its highest. And always stick as closely as possible to the same timing for tests from now on.

If you normally take levothyroxine first thing in the morning, delay taking it until after your blood test.

If you normally take levothyroxine at night, then don't take it the night before, take it immediately after the blood test instead. Then take your night time dose as usual that evening. i.e. The day before testing don't take levo at all, the day of the test take two doses - one after the test and one at night as usual.

A further point, for future reference... If a doctor or nurse ever tries to spring thyroid function tests on you without warning, then refuse them until such time as you have had a chance to miss a dose of levo in preparation.

[Barrister]

Thanks. Clemmie