Thyroid UK
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t3 and heart problems

i want to share my findings on how t3 meds affect heart, i was 10 days on 25 mcg t3 , i had no gradual change from 150 mcgt4 to 100t4+25t3 combination, and i took my all dose in the morning

when i experimented splitting the dose i had some sensations that scared weakness, like i will die

how the transition to 100+25 combo went: i had hunger attacks in the middday exactly 5-6 hours after breakfast, i had to eat! so it was a must! other then that i did not notice like worriesome

i did feel sensations around chest area but sporadically and short lived, and reading the forum talking to people made me worried , becasue people talk of gradual change to t3, and heart problems in connection to t3

so this morning i took 75% of my dose, 18.75mcg

the symptoms were:

dizzines, vommiting, sens of dhiarrea, weakness, that weakness scares me the most..shortness of breath, like i have to gasp for air early in the morning, on 25 it happened only in the evening

now this makes me sure that heart is very sensitive to even slightest chnages in serum t3 this is why people afraid of taking t3 all in one dose, and making gradual chnage, my feeling is for body is better to take it all in 1 dose closer to its optimum , becasue there is constant flow of t3 in serum, and what body does register as heart problem is lower t3 too!!

and here is the list of symptoms of heart problems one should not ignore:

5 Replies

Ivy, how to dose T3 is very individual. Some people are very sensitive to T3 and can only tolerate small frequent doses throughout the day. Others are able to tolerate high levels of T3 in one dose.

I had no problems taking 40mcg T3 with T4 in one dose but my endo suggested it would be physiologically better to split 2 x 20mcg T3. I take the second dose 12-14 hours after the first and notice neither benefit nor adverse effect between single and split dosing.


i agree there, everyone has different D enzymes and different rate of conversion from t4 to t3,so dosing between t4 and t3 is individual, also the total amount of both depends on the hypo state in each patient, but i will stick to my first beliefe conservative approach is t4+t3 in some combination

but the body produces around 100 t4 and 30 t3 , this kind of ratio 3.33 i found in my blood coincidently between ft4 and ft3?....there is something in that ratio for avergae person, and staying around those levels especially when trying to find your own combination should be safe for heart .......and will not cause atrial fibrilation and such things,

my assumption is the more you split lower doses like 25 mcg the more suspect you are to chnages in t3 serum dose and more heart symptoms you may feel......


Ivy, I tend to agree that once your cells are flooded with T3 you are less susceptible to the peaks and troughs of oral T3. I occasionally forget to take my nighttime dose and don't notice the lack. Occasionally I need a 10mcg dose in the afternoon to calm palpitations or because my energy has slumped.

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yes thank you very much , this is what i noticed too.....this scares people off from t3 maybe....and its patience that is important people tend to shift doses like i did and get all sorts of feelings of changing dose ....when one needs to be 2 months on one dose to see if there is under medication or overmedication...but this was great piece of info for me to know what kind of dose is that body produces..and that really fit with my experience.....

the other day i did some exercising and i felt that the regular dose was weaker on that day...lack of t3 translated into not so good sleep that night....the next night was good....but today i am not so good :) so even if i will add to get 25 mcg daily...this is not the same as taking 25 in the morning as i did it for 8 days.....

i think you maybe dont notice if you miss small dose becasue you are allready taking 40mcg which is slightly more maybe then you need on that particular day....dunno just guessing.....i still can not comment on t3 only therapy i really have no experience of that....

so i really want to share all that is proven on my skin :)

this is what i wanted to share with people, there seems to be too much confusion around t3 and its effect on heart......


Ivy, I'm thyroidless and wasn't converting on T4 only hence taking T3. I've been on this dose since April and I haven't felt overstimulated. I'm sufficiently replete to not notice the odd missed dose and wouldn't hesitate to reduce my dose slightly if I felt overmedicated.


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