Thyroid UK

Did I understand why I felt worse on Levothyroxine?

My understanding is that with Levo (T4) TSH is suppressed so the bloods look fine even if you are a poor converter (which I am). Does it also mean that if you have a thyroid, which I have, that any ability it may still have to convert to T3 is also suppressed? Is that why not only did it not work I felt worse on Levo than on nothing? Rosie

2 Replies

Yes, your own thyroid produces hormone IF there is TSH to stimulate it. Once you take any thyroid, whether it's T4 or T3, you suppress TSH somewhat. When you suppress it close to zero, your own thyroid won't make much. Some people are given such a low dose of levo that they would be better off running on their own power. All the levo did was bring their TSH into range. Only if FT4 and/or FT3 were measured and looked at, would one see that there was no improvement . . . only TSH fell into range.

Here's a graphic that explains it better:


Thank you for that, all the best . Rosie


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