Should I take thyroid medication before blood test?

[mrspickle]

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

[mrspickle]

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.

Thanks,

Yolande

[Barb135]

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.

[craigdog]

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.

[mrspickle]

Thanks for the answer.  

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

Hope you feel better soon.

[Barb135]

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.