Parts 2 + 3 of Dr. Tania S. Smith's post on ratios of T4/T3

[PR4NOW]

A further look at the point in question. PR

Part 2 thyroidpatients.ca/2019/05/...

Part 3 thyroidpatients.ca/2019/05/...

[Greekchick]

Thanks for posting!

[helvella Administrator Thyroid UK]

Quickly looked at Part 2 and wanted to make a universal point:

We so often see T4:T3 ratios discussed without first defining whether the discussion is about a molar ratio or a weight ratio.

For example, a ratio of 100:20. A molar ratio can be looked at as number of molecules. This could mean 100 molecules of T4 and 20 molecules of T3.

But a weight ratio might be 100 micrograms of levothyroxine and 20 micrograms of T3.

Trouble is, a molecule of T3 is only 83.8% of the weight of a levothyroxine molecule.

OK, so this is "only" around a 16% difference. But that means 25 micrograms of levothyroxine has the same number of molecules 20.9 micrograms of liothyronine.

Trouble is, if someone doesn't state this, doesn't understand this, what are they doing writing about thyroid hormones and prescribing? And justifying their decisions based on arithmetic which is not soundly based?

Of course, the "as much as you need" mantra is so very important. If you are not getting that, it doesn't matter two hoots what any ratio is! But understanding can help in getting from wherever you are to somewhere closer to what you really need.

[Greekchick in reply to helvella]

This is helpful - I am trying to balance my Synthroid/Cytomel ratio at the moment and will use your formula to assist. Thanks as always.

[Judithdalston]

I like this woman’s writing...easy to read and understand...just hope she becomes more influential in future years and her ‘debunks’ and criticism of modern thyroid treatment becomes more universally recognised, and appreciated!

[jimh111]

Thanks for posting, the website is interesting and has a welcome clarity and science base. The 20:80 ratio of T3 from thyroid secretion v. deiodinase is subject to variation within and between individuals. Unfortunately, as the article advocates this ratio is seen as a therapeutic target (at least when the doctor is willing to supply T3). There is an attempted therapeutic determinism in endocrinology: patients MUST recover with typical thyroid hormone levels. Unfortunately, this is based on a poor understanding of thyroid hormones, made worse by the belief that we really do understand hypothyroidism.

Without needing to understand the ratios of T3 supplied by the thyroid and by peripheral deiodinase it would be perfectly possible to provide tablets that accurately restored normal daily serum T3, T4 levels. (even if the patient had to pop tablets every 30 minutes!). This would still leave many patients unwell. The truth is not all cases of hypothyroidism are caused by abnormal serum hormone levels. (If we accept ‘hypothyroidism’ being defined as inadequate thyroid hormone action). Many patients require abnormal fT3:fT4 ratios. Some patients require supra-physiological hormone levels. I’ve no doubt these therapies are associated with some risk, perhaps greater risks in the absence of therapy. Rather than demanding that patients conform to typical hormone profiles endocrinologists should be seeking to figure out why these patient groups require abnormal hormone profiles to recover.

[diogenes Remembering]

Her criticism of the Pilo article which currently defines the average T4/T3 ratio directly produced by the thyroid was very well founded. We ourselves have criticised this article and the universal unthinking acceptance of its findings and the false implications for therapy. We have I hope devised a better and simpler way of not only revisiting this problem, but also the possibility of finding a range of proportional T3 supply from the thyroid in healthy patient panels. Pilo could only find an average, whereas it is the permissible range that is important to show how different people can be in this regard. This in turn has implications for best therapy when the thyroid fails.

[PR4NOW in reply to diogenes]

Diogenes, I take it this will be discussed in one of the upcoming papers of yours? PR

[diogenes Remembering]

No, it is an ongoing study which has only recently begun. It will take some time to cpmlete depending on frequency of suitable patients.