So confused! How important is your tsh labs compared to your T4 or T3 labs?

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I've been having issues with my thyroid medication and getting on the right dose! I was on here a few months back bc I was over medicated and was going through a lot of horrible side effects! I had my thyroid removed 20 + years ago when I was a teen, and have always been on levothyroxine! Through out the years it has been adjusted! In March I found out my tsh was at 52 and my meds levothyroxine was upped a dose. With in a couple of weeks I felt horrible, so went to get labs and my tsh had dropped to .14 and my T4 was at 1.9 so they dropped my dosage! The dosage since then has dropped a few times and I'm now on .100mg of levothyroxine!

It's been about 6 weeks on this dose and I did labs came back at tsh of .14 but my T4 Free is at 1.4 and T3 Free at 3.1 which says it's in normal range!

So is it ok that tsh is at .14 and but T4 and T3 is normal???!

So weird that when I was over medicated my tsh was also at .14 and my symptoms where bad, but my T4 was above normal at 1.9! I don't know why I felt so bad and wonder if it's bc the dosage at that time was too high and my labs changed fast in a matter of 2-3 weeks!

Since on this dose my tsh has been getting lower but gradually!

I'm waiting for my endocrinologist to call, bc I'm so confused!

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  • Posted

    Hi selina59300, you are probably aware of this, I just mention is as an introduction.

    Since your thyroid was removed you are taking the thyroid prohormone T4 (Levo-Thyroxine or L-Thyroxine). This is converted by your body to the thyroid hormone T3 (L-Triiodothyronine). T3 is about 40 times more potent than T4 and regulates your metabolism. If your T3 (which in your case correlates with T4) is too high you are likely to get symptoms of hyperthyroidism.

    If your T4 is high then your pituitary gland tries (in vain) to stop the overproduction of thyroxine. It does this by lowering the level of TSH (thyroid stimulating hormone). Conversely, if your T4 is low then your pituitary gland tries (again in vain) to ramp up the production of thyroxine by releasing more TSH.

    In healthy individuals, the level of TSH gives an indication of the thyroid hormone level. However, in Graves' disease patients, TSH can stay suppressed even they are euthyroid. 

    "Antithyroid treatment for Graves’ hyperthyroidism restores euthyroidism clinically within 1–2 months, but it is well known that TSH levels can remain suppressed for many months despite normal free T4 and T3 levels. This has been attributed to a delayed recovery of the pituitary-thyroid axis. However, we recently showed that the pituitary contains a TSH receptor through which TSH secretion may be down-regulated via a paracrine feedback loop. In Graves’ disease, TSH receptor autoantibodies may also bind to this pituitary receptor, thus causing continued TSH suppression".  Cited from  Suppression of Serum TSH by Graves’ Ig: Evidence for a Functional Pituitary TSH Receptor, J Clin Endocrinol Metab (2001)


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    • Posted

      Wow thank you that's a lot of info!! So I'm wondering still if this is bad, for my tsh to be at .14? I wish my Dr.'s or especially my endocrinologist would explain this to me! I've also tried researching for myself! It's so complex! My thyroid was removed bc it had a cancerous growth on one side but they removed it all, in 97 and I had radiation in 2005! Last march was the first time I had ever been over medicated! I ended up getting labs bc I wanted to make sure my iron levels were good bc I became vegan! Turned out my tsh was at 52, my Dr. ended up upping my dose from 125 to 137. I've been at 137 before for years but was lowered my last pregnancy 4 years ago. 2 weeks in I was feeling horrible! I had anxiety, rapid heart beat I couldn't sleep! About 3 weeks of taking the 137 I got labs and my tsh had went down to .14! I actually stopped the levothyroxine for about 3 weeks until I started seeing a endocrinologist and by then my tsh went back up to 39! Since then my dose has went down to 100. I've been on that for about 6 weeks! With in those weeks my tsh went from .47 to .14 and I took my last labs 6/26 which was about 5 weeks on that dose!!

      I get worried that I might start getting the hyper symptoms I had before!

      Also my antibodies on my labs are also marked for out of range at 14 H which I have know idea what the means, don't know if it matters bc I don't have a thyroid! Another thing my Dr.'s haven't explained to me! I talked to my endocrinologist and he just said stay on that dose and only take half on Sunday! Thanks again for all the info, it's very helpful!

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    • Posted

      As far as I can tell, your level of 0.14 is not bad per se as long as your endocrinologists are aware that they should not adjust your L-thyroxine dose based on your TSH level alone. They should also measure your FT4. 

      That is because your TSH might be suppressed even if your FT4 is in range. 


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