Thyroid UK
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Thyroid blood results cause for alarm?

Hi everyone,

For the past 3 months my endo has had me on t3 medication, 20mg of Tertroxin, twice a day. I have been back to him twice since starting the medication and both times he has not been alarmed by my blood results and told me to continue with the medication. Yesterday when I saw him he asked me if I wanted copies of the results and of course I said yes. I didn't take note of them during the consultation since he said everything was fine but when I arrived home I had a closer look and saw the following:

TSH 0.04 (.5 - 5.0mU/L normal)

FT4 7.7 (11.0 -22pmol/L normal)

FT3 13.7 (3.1 - 6.4pmol/L normal

TgAb (<115IU/mL normal)

Although I had my last T3 tablet only 2 hours before having the blood work done ( he said just take the tablets like normal on the day of the blood test) these results still appear concerning. My TSH and FT4 appear completely suppressed whilst my FT3 is sky high.

I don't feel any odd symptoms. No heart palpitations and I am sleeping fine. I have a slight persisting headache but that is normal for me. No weightloss

Has any ever had results back like this?

Thank you

3 Replies

sonyalee When having thyroid tests, T3 should be left off for 12 hours before the blood draw (Levo 24 hours). So by taking your T3 two hours before your result is falsely elevated. Even allowing for this, your FT3 would probably be over range if you'd left the 12 hours since last dose.

You might want to retest, ensuring that no T3 is taken in the preceding 12 hours.

Long term over range FT3 can be detrimental to health.

TSH and FT4 will generally lower when taking T3..


Your result is perfectly unsurprising. TSH is suppressed when you take T3, and T4 is irrelevant. Your T3 is sky high because you have just taken some, and it hasn't entered the cells yet.

If you test again at least 12 hours after taking meds most of the FT3 will be inside cells doing it's job. What remains in the blood will be what is left for uptake when needed, plus the product of conversion, so your base level, in effect. And that is the meaningful result.

We measure the T3 in the blood because it's difficult to measure cellular levels. So it's not a direct measure. But if you test too soon after taking the tablets, it's pretty meaningless.


i think results are fine, i had a test done 4 hours after t3 and it was 10 but the test done few hours later was 3. I burn thro t3 very quickly. Whats more important is how you feel. My tsh is 0.02 and t4 9 so your tests look similar to mine.



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