Follow-on from last posts

[diogenes]

I posted recently about a large study where higher FT4, but no other tests such as TSH and FT3, had an influence on atrial fibrillation likelihood. We've now had a paper on the same lines and with basically the same conclusion accepted by Frontiers in Thyroid Endocrinology:

Front. Endocrinol. | doi: 10.3389/fendo.2020.542710

The two faces of Janus: Why thyrotropin as a cardiovascular risk factor may be an ambiguous target

At the moment it is only in preliminary (title) form. It criticises another study which concluded that it was TSH that was the link rather than FT4. Reanalysing their data, it again seems that this isn't so, and high FT4 is truly the link to cardiovascular problems (small as they may be).

[Kitten44]

That's interesting. My endo was freaked out about FT3 going slightly over range and TSH being barely detectable, and argued the risk of arterial fibrillation (even though my RHR drops rapidly to mid-low 50s whenever I lower T3).

So, if a high FT4 is the real risk factor, current (questionable) arguments against the use of T3, or maintaining TSH within a certain range are losing traction?

[diogenes Remembering in reply to Kitten44]

Yes, they certainly are. First the TSH-linked studies have now been shown to be badly statistically presented, and only in this latest paper from Anderson was FT3 measured and found to have no influence, if kept in the reference range.

[tattybogle]

Congratulations, and thankyou for checking their homework. It's no wonder they don't want GP's checking FT3 since when they do it keeps contradicting the God of TSH.

[jezebel69]

I found this very interesting. I recently had a very hyper episode where my FT4 was very high but my FT3 was in range. I take T3 only and my endo (before he retired) never did blood tests at all. What would be the reason for such high FT4?