T3 and DIO2 gene.

[Alejandrita17]

Hello folks!

I have the following doubt:

Does FT3 get lower in ALL patients on Levo alone, or just in a special sub-group?

In other words, does the fact of taking the pill lower the Ft3 level, so that EVERYONE ends up with a lower t3 than in healthy individuals?

Thanks!!

[DippyDame]

In other words, does the fact of taking the pill lower the Ft3 level, so that EVERYONE ends up with a lower t3 than in healthy individuals?

No!

Basically...

Taking Levo/T4 ( alone) does not lower FT3 level.

It is a low serum level of T3 that results in low FT3

However, if T4 to T3 conversion is impaired then serum T3 will be lower ( to varying degrees)

In healthy individuals T4 ( the storage hormone) is converted to T3 ( the active hormone )

Poor conversion results in lower T3

The level of conversion can be impaired by the presence of the Dio2 genetic polymorphism.

If that variant is inherited from both parents then the impact on conversion is thought to be greater than if inherited from just one parent

Therefore the greater the impact Dio2 has on conversion the lower the T3 will be.

It has nothing to do with taking a T4 pill per se but everything to do with the body's ability to use that T4

In other words, the presence of the Dio2 gene can influence the body's ability to convert T4 to T3

Low T3 results in a low FT3 level.

But only a low cohort of patients have the Dio2 genetic variant.

Research has shown that those patients may benefit from replacement T3

This might help

pubmed.ncbi.nlm.nih.gov/191...

"Common variation in the Dio2 gene predicts baseline psychological well-being and response to combination thyroxine plus triiodothyronine therapy in hypothyroid patients"

So, not EVERYONE that takes T4 ends up with a lower FT3 than healthy individuals!

Hope that helps.

[tattybogle]

I doubt anybody has enough data to definitively answer that question .

and there 2 difficulties with the question...

a) with comparing any individuals blood results on levo to their previously healthy results.

Your case is unusual in that your thyroid was healthy then instantly it wasn't.... so you are fairly confident that your 'before ' results are consistent with your 'healthy' T3 : T4 ratios.

But It is rare for anyone with autoimmune thyroid disease to have a record of their 'healthy' pre disease TSH level and T3 : T4 ratio.

Even results taken several years before levo may still be somewhat abnormal in autoimmune thyroid disease patients, due to 'compensation' happening before the person felt symptoms.

So there's not going to be much data comparing individuals healthy / post Levo T3:T4 ratio.

b) The vast array of difference found among 'healthy' individuals T3/T4 levels / ratio's (as seen below in a sample of just 10 people).... means making any sort of generalisations about what happens to their ratio's after taking Levo a bit of a wild goose chase.

Diogenes published papers are ? probably the best place to look for as good an answer as you can to your question. .... but i think you are asking about something that is far too individual and complex to have a yes /no answer for EVERYONE .

,

[Alejandrita17 in reply to tattybogle]

Thanks very much, Tattybogle.

If You have low-normal FT3, which tissues would be mostly affected?

BRAIN or other peripheral tissues?

I'm just trying to figure out if my ongoing "night jerks" are related (or not) to this "new level" of t3 I have. In other words, if low normal T3 is affecting my Brain somehow.

It is basically the only symptom I still have.

[tattybogle in reply to Alejandrita17]

To be honest , i don't know ~ i still get lost when i try and think about 'which tissues/organs are effected most by what' .

I know the brain does something different to other bits .... i think? the brain 'prefers' to convert it's own T3 from T4 in situ (but i could have remembered that bit the wrong way round.. i think jimh111 knows)

And i think the different deiodinase's can be turned up or down in different tissues at the same time. so eg low T3 /high T4 will not affect all tissues in the same way.

So i'm not much help with the 'theory' for what you are trying to figure out.. sorry.

But theory will only ever take us so far .. with something as individual and under researched as thyroid hormone replacement there comes a point where the only answer is "go with your gut feeling , suck it and see"

...... and if your jerks reduced when you got your T4 and T3 levels in a more 'natural' balance with each other , and if you can achieve this without plummeting your TSH to supressed levels that freak you out ...then you have your answer. The relatively low T3 was probably involved in the jerks.

The thing is , even if there was somebody else on here with exactly your blood results and exactly the same previous history, on same dose Levo .... who found their jerks got better when they got their T4 T3 more in balance to each other..... it still doesn't mean you would react the same ... one of you might find an improvement and one of you might feel worse ... and nobody would currently be able to tell you why .

It just depends.... is it a bad enough problem that experimenting with your thyroid hormone dose is worth it to try and fix it , if it is .. have a go for year and see what happens to your jerks.. if it's not and you're nervous of rocking an otherwise 'OK' boat ...leave well alone. and count your blessings that levo is fixing most things well enough that you can get on with your life .

[Alejandrita17 in reply to tattybogle]

This is my series.

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