Thyroid UK
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Do blood results indicate use of T3?

Hi everyone, did post a while ago but wondered if anyone could offer opinion on blood results.

Latest results were whilst on 75mg levo.

Serum tsh 3.37. (0.35-4.94)

Serum free t4. 13.1. (9.00-19.00)

Serum free t3. 3.2. (2.6-5.7)

Thyroglobulin autoantibodies 54ku/l

Serum thyroglobulin 7.7 ug/l

Thyroid per oxidase <10iu/ml

Now trying combination of 50mg levo(after advice from this site) and 5mg t3. I did first try 75mg levo with 5mg twice daily but felt very anxious , jittery. Think perhaps too much as also have adrenal issues.

Would appreciate thoughts on what, if anything , actual blood tests suggest. Thanks. Take care all.

4 Replies

Blackcap, the thyroid blood test can't tell what type of thyroid hormone replacement you are taking.

TSH 3.37 means you were undermedicated on 75mcg Levothyroxine (T4) and your FT4 and FT3 will inevitably be low for that reason. Reducing T4 to 50mcg and adding in only 5mcg T3 means you are taking the equivalent of 65mcg T4 so your TSH is likely to have risen above 3.37.

I would advise increasing T4 to 75mcg and continuing with 5mcg T3 for 6 weeks and have another thyroid blood test. If you need an increase it will have to be T4 if adding more T3 makes you feel jittery. T3 doesn't suit everyone.

Thyroid peroxidase antibodies are negative but you haven't included thyroglobulin antibody range so I can't determine whether it is positive or negative.


Thanks clutter, understand it a bit better now. I do wonder whether to try another dose of T3 (5mg) at lunchtime first with the reduced thyroxine, see if this avoids the jitteriness. If still same outcome think def need to increase t4. Prior to sept I was on 125mg of levo, tsh of 0.03. Then reduced to 100mg with tsh of 0.10.

Re thyroglobulin it just says >46 suggests potential interference and be interepted with caution. For serum thyro level says>1.0 may indicate recurrent/residual thyroid cancer or persistent thyroid remnant. Also says if tg is >0.1 and serum tab>20 the result may be an underestimate of true value. Serial monitoring of both tg and tag is recommended.

Does this make sense to you? I was worried at first but gp does not seem concerned, by own admission says beyond her!


Blackcap, It's not very reassuring that your GP isn't concerned because she doesn't understand the test and results! Thyroglobulin serum testing is only of value in testing thyCa patients after thyroidectomy and RAI which are supposed to destroy all thyroid cells. It's used as a cancer marker and if thyroglobulin is >1.0 and thyroglobulin antibodies >20 it means there are thyroid cells present and possible recurrence of the cancer cells.

Thyroglobulin antibodies >46 means you are just positive for autoimmune thyroid disease (Hashimoto's).

Certainly increase the T3 to see how you tolerate it but bear in mind that a 5mcg increase will only put you onto the equivalent of 80mcg T4 so you will need to increase T3 or T4 further.


Thanks clutter for explanation. I don't really know much about hashimotos, as only just in positive range does that mean do not need to be concerned or is it a level that changes often ? I had been suggested my hypo might be auto immune as have previously had endometriosis which is also an auto immune disease I believe.

Sorry for all the questions, been feeling ill for so long with diagnosis of M.E, mito issues and also adrenal fatigue so difficult to know where to turn. Would just be good to wake up and feel well one day!

Couple days ago I increased t3 by another 5mg, wondered how long should leave before upping t4 also as would still be under medicated?

Any advice appreciated. Thanks.


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