Stopping levothyroxine in people taking it regularly causes an initial increase in FT3 levels.
Could this phenomenon be behind the frequently posted cry that people feel better when they stop levothyroxine? (Though all too often followed by feeling terrible a few days later.)
Quick summary from Healio here:
Data from a small pilot study indicate that short-term withdrawal of levothyroxine was associated with higher plasma thyroid-stimulating hormone levels and an increased free triiodothyronine to free thyroxine ratio.
Full paper freely available here:
(It is possible that either or both links require you to sign up to Healio. I was signed up, for free, to at least one of the forerunners of Healio and cannot really remember what happened.)
I feel I need to emphasise that this is absolutely NOT a recommendation, nor even a suggestion, that anyone changes their thyroid hormone medicine on the basis of one small, though possibly important, study.
Image is a graph from the paper itself.