Thyroid Disorders Community
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Avatar universal

Should I take thyroid medication before blood test?

I am due to have a blood test to measure my thryoid levels in the next few weeks. I currently take 50mcg T4 per day and 5mcg T3 (in 2 doses 2.5mcg AM and 2.5mcg PM).  

The blood test will be first thing.  Should I take my thyroid medication before the test?  I'm worried that taking these doses before the test (esp the T3) will produce results showing higher thryoid hormone levels than I normally have during the day.

Thanks in advance for any info
5 Responses
649848 tn?1534633700
It won't matter that much about with the T4 med, but don't take the T3 prior to the test, or you will have a false high, since T3 is pretty fast acting. Main thing with T4 med is to be consistent.  Don't take T3 prior to labs.

I had to cancel my appointment yesterday for blood work, because I didn't think and popped my T3 med about an hour before my appointment...... Rescheduled my blood draw for today and didn't take either of my meds before I went; then forgot them when I got home.... but that's okay because my blood draw was late morning....... I did miss the T3 and have felt tired/groggy most of the afternoon.
Avatar universal
Thanks for the answer.  

Ok, so miss the morning dose, but ok to take the night before.  Got it.

Hope you feel better soon.
Avatar universal
I took my T4 at 7am and had my blood draw at 1pm today. This is the first time I haven't had the draw first thing in the morning. We'll see what the results say tomorrow. I agree with Barb, it shouldn't make much of a difference.
649848 tn?1534633700
Just to clarify -- taking T4 med prior to a blood draw won't make much difference......... if you are on a T3 med, do NOT take it the morning of the blood draw, no matter what time of day the draw is, because you don't know how long it will stay in your system.
Avatar universal
Thanks very much.  I understand.  I usually take my T3 PM dose at 5pm.  The blood test will probably be at 7am the next day. Do you think I should miss the PM dose the day before too, just to be on the safeside.


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