Research and resources into bio chem of needing T3 to convert T 4?

Hi team thyroid. I am now on T3 T4 combo and did not feel much improvement after a week, they r also checking out my parathyroid cos of raised calcium in blood! While taking blood nurse noticed large hump on base if neck between shoulder blades. Its a classic sign of cushings symdrom, possible tumour on pituitary!! So today waiting to hear if I need further investigation on a further two endochrine parts as a result of having no thyroid( papillary cancer ) and only ever been given T4 and no T3 to convert it.

Slight goid news is excessive cortisol may be at root of lot of my painful symptoms.

This life threat had made me want to know more about my case which seems cut and dried to me- without any thyroid I cant make T3 so was neverv able to convert T4!! I want to document this medically because this is utter medical negligence and set me up to be very ill. Like a mechanic never putting oil in the engine and telling the driver that the car will be fine just keep putting in petrol. My engine is completely seizing up!!

Medical resources wld be great!

15 Replies

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  • If you cannot convert T4 you may have the defective gene and I'll give you a link. This would mean that you should be prescribed T3 only. I have never been diagnosed with a defective gene but the fact that I feel well with T3 only makes me think I have. I always had symptoms with all other trials I had with other thyroid hormones.

    thyroiduk.org.uk/tuk/testin...

  • Really interesting.

  • I am still trying to nail this for me sorry! New to the whole biochem. Is this biomedical fact, I need T3 to convert synthoid T4 as it is an inactive hormone. So following thyroidectomy and RAI having absolutely no thyroid celks my body wld never ne able to convert T4 to T3 without combination treatment. So why isnt this standard treatment pist thyroidectomy and why are BMA arguing against T3? I ambsoery if I keep repeating myself but this is so nuts and I am so ill and cant understand given to biochem i am reading why I have been made to suffer for so long! This has never been a suspective under active thyroid case or genes causing malfunction, I dont have one! If Drs knew because ofctheir biomed studies that I would not be able to convert what exactly is the issue prescribing T3 to those of us who they kniw cant physiologically convert because we dont have a thyroid!! I keep coming back to this fact and cant get my head around it

  • Plenty of people who have had TTs are on T4 only, as are plenty of people whose thyroid is dead for other reasons, and do perfectly well. This is the first time I have ever heard this suggested.

    Where did you read this? Do you have a link to the research?

  • I've found lots of information on thyroid patient advocate.

  • I think maybe you've slightly misunderstood something you've read. T4 is converted to T3 by certain enzymes, the deiodinase system. T4 has 4 atoms of iodine. To make T3, one atom of iodine is removed. As far as I know - and in all my years of reading I have never read the contrary - the existing T3 has nothing to do with it.

    If you have found lots of information - and I couldn't find any such information on that site - why don't you use what you've got to convince your doctors?

  • I'm very confused at this point and ill so more than likely I've misunderstood.

  • I do realized I may be a poor converter genetically which may have caused the original cancer. Thanks for the clarification!

  • Lots of us are poor converters, for lots of reasons. I'm a bad converter, and no idea why. But, I don't really think that being a bad converter causes cancer.

  • It's easily done. It's all very complicated. But, the important thing is, you've got some T3 now. :)

  • Sarahpk,

    Most people are well on Levothyroxine only after thyroidectomy or RAI. Some thyroidless patients may need T3 in addition to Levothyroxine if they are not converting sufficient T3 and so will poor converters who still have some thyroid function. It doesn't matter why one is not converting well, the addition of some T3 to Levothyroxine will over come conversion issues and raise FT3.

    One week of taking T4+T3 isn't long enough to tell whether the combination dose is right or whether it is working for you. You need to allow 6-8 weeks.

  • Thank you very much, its great to have these guidelines. :)

  • I'm realising for my own information the gene test could answer some questions.

  • If you want to replicate a normal thyroid gland's output, you would prescribe T4:T3 in roughly a 10:1 ratio, or whatever ratio works. T4-only is a 10:0 ratio. T3-only is 0:10 ratio. You've read correctly that T3 stimulates conversion. It has to do with the deiodinase enzymes that do the converting. Just like your T3 and T4 levels affect your TSH, they also affect the deiodinase enzymes that perform the conversion. There's some info here, with references about the deiodinase enzymes: tiredthyroid.com/blog/2016/...

  • I really want to get to the root of this to challenge how in my case they can deprive me of NHS T3 . Not just me but others in same boat. I think I will get the gene test and hope it is poor convertor, i am so ill and the International Thyroid Scandal has got me here

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