Reverse T3 testing - how long before should I take my meds?

[Petriz]

Hi!

I am taking a Reverse T3 test for the first time. I take both T4 and T3 medication, and have been told I should take my T4 meds 24 h before testing and my T3 meds 13 h before testing to get accurate results. But how long before testing Reverse T3 should I take my meds?

Thankful for all ides, this test is expensive and do not want to mess it up!

[MaisieGray]

You have to test RT3 at the same time ie in the same blood draw, as your TSH, FT3, and FT4 are being tested. Knowing your RT3 level is of dubious value in any case as it only tells you the level but not why it is at the level it is - and there can be many reasons including non-thyroidal ones such as dieting, having another unrelated chronic illness etc etc; but you need to know the level in conjunction with the others to begin to have a sense of what is going on. So consequently, the same guidance applies - no T4 for 24hrs before the draw, no T3/NDT for 8-12 hours before.

[Redporti in reply to MaisieGray]

What time of the day should you get the test done & does it have to be fasting? I’m only on T4 meds that I take at 2am. So would I have to skip that dose & then take the next dose the following 2am? Thanks.