Thyroid UK
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If I skip an NDT dose - will it affect my blood results?

I have an appointment Friday morning to get my thyroid panel re-checked (last one was 6 weeks ago), but still have these bloomin ectopic palpitations. My question is, if I skipped my dose tomorrow, and then resumed Friday after my appointment - would this affect the results at all? I was trying to hold out on the 1.5 grains I'm taking, as I have cut down by half since my last test as my FT3 was a bit high. I was hoping cutting down by half would have made a difference - and for a while it did, but they are back again :(

3 Replies

Sip, you should allow 24 hours between your last dose and your blood test. TSH and FT4 levels will be right but FT3 will be slightly falsely low as T3 leaves the blood stream after 6 hours or so.


Ah ok - oh well, I'll just take it as usual then tomorrow. My appointment is 9.30 (not particularly ideal but that's all they had). I usually take my NDT about 6.30 - 7 am. Should I take it a bit later then, about 9.30 instead? Thanks for replying :)

(I mean the day before the test obv :) )


Sip, it's up to you. I can't see it will make much difference whether you take it at 6.30 or 9.30 in terms of the test :)


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