On T4/T3 combo, TSH suppressed, diagnosed with atrial fibrillation, caused by 'subclinical hyperthyroidism'

I've had a horrendous few weeks since I developed atrial fibrillation (AF), being in hospital four times. This is a very alarming condition, not helped by my hyper sensitivity to the drugs that have been prescribed for AF. I was on 110mg T4 and 10mg T3 per day (T4 100mg daily and 25mg three times per week). As my TSH was suppressed the cardiologists and endocrinologist think that the AF was caused by 'subclinical hyperthyroidism', over treatment. I am 61 and have resisted attempts to reduce my thyroid medication as I felt ok, although I have been more tired recently, which I now realise can be a symptom of over treatment. I stopped the T3 and it's suggested I reduce the T4 to 100 - am waiting for my blood test one month after stopping T3.

Now I feel rubbish, shaky and dizzy. I took my temperature this evening and it was 36.1. I have been on the T4/T3 combo for about 15 years. Was the T3 contributing to the heart arrhythmia as it is fast acting and causes peaks? Or was it simply that the TSH was suppressed so I was generally over treated, post menopause? But perhaps I need the combo and should reduce the T4 instead and resume the T3? ( At some point in the future- currently will have to sit it out, want to avoid exacerbating the AF at all costs).

I feel an idiot for ignoring the GP's advice to cut down, but on the other hand no-one really explained all the risks to me.

31 Replies

  • Coachv,

    The Rotterdam Study finds no association between TSH and atrial fibrillation. press.endocrine.org/doi/abs...

    You can email the Endocrine Society for free patient access to the full text of the study.

  • Thank you clutter! All grist to the mill - I save so many refs! Happy New Year! xx

  • Thanks for the reference Clutter. However, there's no need to contact the Endocrine Society - just click on the link that follows the abstract, namely:http://dx.doi.org/10.1210/jc.2015-2480

  • Thank you, Tcpace, previously the full text was only available via email request.

  • Hi Clutter

    I am not a medic but it seems that this is still a controversial issue. I may have misread the Rotterdam article but it seemed to exclude people with suppressed TSH.

    For example these articles find association between subclinical hyperthyroidism and AF eje-online.org/content/152/...


  • Coachv,

    Those are much older studies than the Rotterdam Study.

  • Hi Coachv - I'm on my way out but have some grasp of what you're going through - my arrhythmia [heart rate way too slow used to be scary - untreated until I used NDT then T3 alone] was likely due to undiagnosed hypothyroidism... apart from inexplicable weight gain and the heart issue, I had no idea there was anything wrong. My TSH is now well supressed and I'm still not 'fixed' but much better since before being treated. I could never take T4 alone and have been taking 62.5 mg of T3, now down to 50 mg per day as a trial.

    This is so, so difficult, not knowing what's best and not really having anyone to advise, other than their 'finger wagging after the event'.

    So, is it that your AF is too fast heart rate? Does anyone give you advice or is it all separate, like the endo for one thing and the heart with someone else? I tried years back to have my GP locate someone who knew about both issues... yeah, you can guess!

    Take care and be well - happy new year too! xox

  • Sorry Coachv - just on way out - you say 'subclinical hyperthyroidism' so heart must be too fast! Mine was slightly over FT3 result and a little over anyway [which is why I've dropped it to 50 mg].

  • I'm not medically trained, but if it were the T3 causing your AF, then it seems to me you would have gone back to normal when you stopped the T3. But I could be wrong...

    Just the act of taking the T3 won't cause AF, it's a question of how much you take. And 10 mcg is a tiny dose. But, you will know more when you get your blood test results. If the FT3 isn't over-range, then it had nothing to do with your AF, I'm pretty sure.

    Besides, you cannot have hyperthyroidism, subclinical or otherwise, because you are hypo. Your gland cannot suddenly start over-producing thyroid hormone, it's physically impossible. And diagnosing 'subclinical hyperthyroidism' just because the TSH is suppressed, is a joke! If your FT3 isn't over-range, you're not any kind of hyperthyroid - or over-medicated, to give it it's correct name. But, you see what you want to see, and doctors hate T3, so they're always looking for excuses to cut the dose or remove it completely. Your AF was a gift from heaven for them! They could blame in on the dreaded T3 and stop your prescription with a clear conscience. Never mind science! lol

    I know we always tend to blame ourselves for these things. But you've been taking that combo for 15 years. Don't you think that if there was a problem, someone would have noticed it before? I presume you have had blood tests in those 15 years. You've done nothing wrong, and you haven't brought this on yourself in any way. It could even be that you were under-medicated, because under-medication can cause heart problems, too! In which case, it would be entirely down to your doctors!

    So, don't got fretting about it until you see your blood test results - oh, unless you have a copy of one with you on your T4/T3 combo! That would be very interesting to see!

    Happy New Year :)

  • HI Greygoose

    I am not a medic but I think that if you are hypo and over treated then you are considered hyperthyroid, it seems to be the term used in articles. Also I think the mechanism of action of T3 on the heart is complex and does not have an immediate effect as you suggest. It may be that I have been slightly overtreated for a long time and it has built up. AF is caused by subtle changes in the heart that seem to evolve and develop. It may not have been the T3, as you suggest, but just the overall effect of me being over treated with both T3 and T4. My GP has been suggesting I need to reduce my treatment as TSH is suppressed but as I felt okay I resisted this advice.

  • Well, we'll never know if you don't post the test results, will we. But, certainly, a suppressed TSH does not automatically mean you are over-medicated. Or call it hyper, if you prefer. I prefer to be accurate.

  • Thanks, I posted my last results in other post. I agree that suppressed TSH does not mean overtreated necessarily, but it might have been for me.

  • If you were taking T3, then the only important test was the FT3. The TSH is totally irrelevant. Did your doctor ever test the FT3?

  • No recently, I will try to get it for the next test. You need special permission from Dr for anything but the standard tests! I asked for T3 but they last time but they did not do Free T3

  • Then your doctor will have no idea whether you were over-medicated, or not.

  • Best to reduce the T3 first. I would be inclined to try a tiny dose of T3 and see how this works out. This would be using 1/8 of your 20mcg tablet = 2.5mcg approx. Use a stanley knife blade to cut up the tablet.

    Dr Blanchard in the USA (writer of a functional approach to hypoT) reckons his patients do best on a 98:2 ratio of T4 to T3. He thinks many patients are over medicated with T3. He does use slow release T3 however, and so we can't get that in the UK, but certainly worth a try.

  • Thanks. I have a friend in the US - do you know if he could buy it and send it to me? Presume he would need a prescription?

  • Not sure if he can buy it from the USA, but you can buy normal T3 in europe. I think you can ask someone for a link on here, maybe a moderator. It is £21 delivered from a site i know about for 100 x 25mcgs.

  • That's a very strange ratio! Do you have a link to where he says that, please?

    Dr Lowe didn't like slow release T3...

  • Thank you for the link.

    OK, so he is uninformed about T3 only treatment. But, that isn't the only worrying thing. That ratio of 98:2? Surely that goes against nature! And, now, marsaday says he 'addresses' taking T4 with food to stop weight gain? That sounds insane! But, I'm not going to buy the book just to read stuff like that. I'll stick with Dr Lowe, thank you very much! lol

  • This guy speaks more sense to me than many other doctors out there.

    Some patients on T4 (or NTH) gain weight. It is a well known issue. He thinks that the T4 is stimulating the stomach receptors too strongly and so more leptin is produced. The patient then goes on to eat more than normal and gain weight.

    His simple strategy for this is to get these patients to take the T4 WITH food. Note, only patients who experience this weight gain issue.

    This issue then goes away. He also notes a slight increase may be needed in meds due to lower absorption, but this issue is not as common as you would think in these cases.

    Why would you be so closed to learning more info on the thyroid. There is so much more to this area, there really are multiple ways to help thyroid patients because what works for one doesn't always work for another. I think it is important to share good practise because it may help someone.

    I myself realised before i read this book that T3 was damaging me in the doses i was taking. Over time i have almost stopped using it (maybe 2 doses of 3mcg per week).

    Your comment about his advise being "insane" makes you sound like a GP talking down to a thyroid patient "i know more than you mate, so do as i say and whatever you have to say must be rubbish". They have their dogma, you have yours.

    I learnt about Dr Blanchard on Dr Myhill's website about thyroid issues. She is very open to new ways of treatment and i think his book must have impressed her as she mentions his stuff on the site a bit. Here is the link:


  • Well, he may think that. But the truth is, most hypos lose their appetite. It's far more likely, as weight-gain is a hypo symptom, that the patients put on weight because they are under-medicated, or can't convert T4 to T3. Besides, with very many hypos, the weight-gain is nothing to do with food, but with mucin/water.

    I'm not close-minded, I've learnt a lot in the 16 years since my diagnosis. And none of this makes any sense according to what I've learnt - although I agree with you, a lot of other doctors talk rubbish, too!

    I may sound like a doctor, but I'm not telling anyone to do anything. I'm just saying that I would not take my T4 with food, or cut out the majority of my T3 - been there, done that, won't go there again. But I'm not against anyone else trying it if they're so minded. Good luck to them! I would be interested to read the experiences of anyone that has tried taking T4 with food and found that it stopped them putting on weight. But I would think that it is very difficult to calculate a dose that way, because you will never be sure how much T4 is being absorbed.

    But, I don't think that Dr Blanchard's ideas should be presented as THE way to go - any more than anyone else's ideas. I think one should say well, why not try it this way, Dr Blanchard thinks it works like this... My 'dogma', as you put it, is that we're all different and have to find our own way. And, you, too, have your own dogma, so don't criticise me!

  • Regarding the T4 and weight. I think you are misunderstanding what i was saying. Yes hypoT causes weight gain usually, but the weight gain Dr B is referring to is the weight gain seen AFTER they start on T4. It is caused by the T4, not the illness.

    So to mitigate this effect the patient who has this issue takes the T4 with food.

    It really is a new approach, one i haven't heard of, but this doc has seen it in his surgery for years and has now written about it.

    It is a simple tip which should be shared with the world, not shouted down. It isn't really relevant to the OP, so i don't need to discuss this issue further.

  • Before joining this site I used to take my thyroxine just before breakfast. I now take it in the night and have lost a lot of weight.This explains why thankyou

  • Interesting thanks. It may also be due to the fact that taking T4 at bedtime is a more natural time to take T4. We have our TSH highest when we go to sleep and the body makes the thyroid hormones in the first part of the night. This also has a knock on effect to the adrenals and so we make more adrenal hormones.

    We replicate what the body does naturally and so end up with a better functioning thyroid / adrenal system. Hence your body may be working as it should more effectively.

    I myself take my T4 at breakfast, the afternoon, and bedtime. I find i get better energy delivery for the different times of the day. I play sport, so the afternoon dose really helps with energy in the evening. If i missed my T4 at bedtime and took it in the day, i really feel worse the next day. So T4 at bedtime is a key foundation for me.

  • I have recently reduced my thyroxine due to this. also all supplements optimal. Onwards and upwards. let's hope 2017 is a good new year for all. I am also vegan and now totally gluten free

  • Well, you're the one that brought it up. And I certainly don't wan to discuss it any further! And I wasn't shouting it down. Don't put words in my mouth, please. End of.

  • Last night I woke at 3 feeling anxious and with ringing in my ears. I decided to take a little T3, cut up a tablet. I am nervous about treating myself but this is after all only a little of what I have been taking for 15 years. I don't want to bring on the AF, but on the other hand I have gone from being a sporty active person to a semi-invalid in the space of a few weeks. I stopped the drugs they gave me for AF as they disagree with me (perhaps because I am hypo) so I am concluding that I have hypothyroid symptoms now after stopping my T3 for all those weeks. I don't know if I still 'need' T3 or am just used to it, but think that a better way to find out is gradual dose adjustment.

  • Why would you no-longer need T3? You can't live without it. It is the active thyroid hormone that every cell in your body absolutely needs, in sufficient quantities, to function normally. No-one stops needing T3.

  • His book is worth reading, a very simple approach. Only written it because he is due to retire soonish. I bought the book on amazon, no links on the net sorry.

    He says the big mistake with T3 is the large tablets sizes made. He says we should be using tablets in 1mcg sizes ideally.

    He also addresses taking T4 with food to stop any weight gain (quite common for people).

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