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Thyroid UK
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T3 meds increase risk of heart problems and arthritis??

Hello there, my endo Has recently told me that because I am unable to tolerate and more Levo, he might be willing to prescribe t3 ooor ndt. However he has said I should choose these options with caution as they may make me feel like a new woman now but as there is no way to tell where the extra t3 will go it can cause problems further in down the line! That synthetic t3 will be prescribed to match the ratio to t4 (can't remember that) but that the t3 in ndt ratio is in excess of this figure and so too much t3 is given again, what does the body do with the extra t3? Does anyone have any thought on this or point me in the right direction to info to enable an informed decision ?

7 Replies

Your body makes T3 naturally, you can't live without it. If you take too much it can be very unpleasant so you wouldn't want to carry on anyway.

In my opinion this is used as a common scare tactic & I have never found any evidence to support it.

Heart & bone problems can indeed be caused by too much T3, but you don't want too much, you just want to replace what your body would naturally make. As long as you have regular blood tests & know what the symptoms of over medication are, I can't see a problem.

I have been on NDT for 2 years


If you do not have a T3 level in your body suitable for your health, and cannot get there by T4 alone, no amount of T4 will suffice, and if you get too much, would actually REDUCE your T4-T3 conversion in favour of reverse T3. There is a logical nonsense in trying to match T3 to T4 in dosage, because no one knows exactly what your amounts and ratios were when you were well. So there is no target to aim for except a very general ratio of about 3 to 3.5/1 free T4 over free T3 which is only an average. Lastly, the important thing is to get your T3 right. However lower than normal amounts of T4 won't matter, because it is an inactive pro hormone, and won't be converted to T3 unless you need it. So long as there is some T4 there for conversion when required, the actual amount won't matter much. As for potential dangers - if you could get to a point of having FT3 normal and TSH normal (round 0.5-1 unit) then the dangers are minuscule to absent (according to accepted thinking) and even if TSH is suppressed then the potential problems of osteoporosis and AF may be there in the future, but at very low frequency - e.g. for OP 1 extra fracture per 1000 patient-years. AF happens quite often in the elderly - usually not due to thyroid problems at all.


This is why T4/T3 is much better then NTH because you can control the ratios you want to take. Some people it seems need more T3 than T4 (or T3 only to feel well), others need T4 only, or some T4 and a little T3. I use mostly T4 and around 5mcg T3 per day. It works very well. I have used more T3 and less T4 in the past, but slowly i have gotten on top of the hypothyroidism and have catered to my bodies needs over time as things have changed.

The body makes about 1-2mcg T3 per hour so this means we make 24-48mcg per day approx. I think if you are more active you will make more. They recommend you take 1.8mcg T4 per KG body weight. So for a 60kg woman you would take 108 T4. How much T3 to take ? Is conversion good or bad ? Best way to find out is to start low and move higher, understanding the higher doses will be pushing what we naturally make.


Sorry, this is such an old thread but I have high reverse T3, and worked out that my ratio was too low or high or whatever (it's a while ago since I did it). But if you reverse that argument, maybe my body is converting to Reverse t3 for a reason? As a protection against having too much T3? I have low but within range FT3 and feel fatigued and cold much of the time.


To make rT3 you have to have some T4 to make it from. You can't make rT3 from T3. So high rT3 indicates too much T4 being taken.


I'm not taking any T4!! My T4 is normal, I think, so why would it convert to reverse t3? I can only think it's a protective thing and this is why I would be apprehensive of taking t3 without supervision. Not that I've ever been prescribed any.


What utter rot! T3 is a building block an active hormone that is essential for all systems.


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