Thyroid UK
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Self medication and heart problems or the great NDP fail.

Hi everybody, I want to warn against self medication and too much T3.

Around 4 years ago I decided to replace my NHS thyroxin with NDP Armour or Nature Throid. I was given a dose of 1 grain and 50 UG of NHS thyroxin and 100 MG of pregenenolone. I felt great, I was puting in sockets in the walls and plastering, we went on holidays and there was no stopping me. Even my GP was pleased my TSH although suppressed, my Free T4 was in the corrects limits. What I did not know my T3 was very high. I would wake up in a sweat and my heart was racing. Around this time last year, I tried to hang a tv on the wall and collapsed with terrible shortness of breath. I went to see my GP and I was diagnosed Atrial Fibrillation.

Lucky, I had a procedure in June of this year that put my heart into paroxysmal AF, instead of chronic, I now get spasms and I am waiting for the results of tests and hopefully early in the new year I will have another Pulmonary vein ablation,

When I get into trouble with my thyroid, I go and see an amazing Endo in South Africa. I have seen him around 5 times now and I will this time do what he says in earnest. I was taking too much t3 which has put too much strain on my heart. He has cut down to a 1/4 grain and 75 mg of NHS t4 (teva|) and other drugs to help me lose weight and control my insulin overload.

So please don't reach for the thyroxin, if you TSH is wrong or you need too much Thyroxin, there is a good chance that is not the cause, It your adrenals or sex hormones, or lack of them.

Please do not over dose. I now have AF, may be two leaky valves and I will have to go into hospital again in the new year. I know its not nice to feel unwell but look at other things, not just your thyroxin.

Take care.

John C

11 Replies


There is only 9mcg T3 in 1 grain NDT and your combined dose of 1 grain NDT + 50mcg Levothyroxine was a very small dose for someone who has had their thyroid removed. It's hard to see how your FT3 could have been too high on the combination.

I certainly agree that anyone taking NDT or T4+T3 combination should make a point of checking their FT3 remains within range.

I hope the procedures will help repair your heart.


Thats what everybody has told me. but my t3 was way to high,. I wonder if my thyroid has regrown form any bits of it that was left in. I heard this is possible. As I have go older i need less thyroxin as shown in my blood tests but more adrenal support.



How high was FT3? It's unusual that FT3 is high if FT4 and TSH are in range.

If you had Graves it is possible for thyroid to regrow and produce hormone. A scan would show whether it has regrown and a radioactive iodine uptake scan would show whether it was producing hormone and causing hyperthyroidism.


It is possible you had an underlying heart condition before the Thyroid issue - it is quite common - when either over or under active ....


All the more need for the T3 to be tested at each blood test. How much would a heart op cost compaired to a blood test?

Best wishes for the op and hope you feel better soon.


I have no thyroid and was taking NDT 3 grains per day for 7months. When I had my FT3 tested it was over the top range by 1/3rd which is high. I did have a much higher heart rate and sometimes my heart was pounding. I am now on 1 grain of NDT and 1 x T3 per day and feel well, so far but thanks for the warning.

I suppose it depends on how long you were on the higher dose as well.

1 like

Yes, I have had heart problems before but did not evert think they would return. I was warned about taking T3 as it put a strain on the heart. My resting heart rate was around 92 BPM for a number of years but its easy to take the meds as I felt so well. That is why I am putting out the warning.

Regards John


Well, I dunno. Most of us seem to have more clue about dosing than some of the GPs mentioned recently. How come you didn't get your free T3 tested? You were on a very tiny dose of t3 and generally it's low T3 that causes heart problems. Do you have Hashi's? I wonder if you had a really nasty flare. Let's hope that the new endo can sort everything out for you.


I was and was warned about over dosing many times. But as you are aware the NHS does not measure FT3 or they do not where I live.

What I do not understand, i have had a total thyroid removal and yet my bloods suggest I only require a very small dose of replacement thyroxin. When very first dr after my thyriod was removed made a calculation weight and experience etc it was suggested I needed 150-to 175 MCr of T4 and it was nothing like that maybe between 75 and 100 MCR.

My south African endo wants me to take 1/2 gain and 50 MCR of T4 but i sleep most of the day and my legs hurt so badly on that dose, that I have upped it to taking 75 MCR of T4 and a 1/4 grain.

I have a blood test in the middle of December to see how I get on with the dose. Interesting my cardiologist wasn't that interested in my bloods, he remarks so you are a little bit high dose on your thyroxin but no too much, I am not worried. Yet the NHS endos and the GP go mad when they see a suppressed TSH.




Everyone is different, I suppose. I can take a lot of t3 for my size and it doesn't seem to affect my results much at all, but T4 makes me feel terrible.


Hi Stockman, for what this is worth I too have no thyroid and I take a very low dose of NDT, 1.5 grains which my Endo thinks is too high and prescribes 1.25 - and doesn't count the days to run out. If I take more than 1.5 I have all of the over medicated symptoms. Oh, and I feel very well and energetic.


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