Diagnosed with paroxysmal AFib in 2021 (in A&E), was on 75mcg Levo and 10mcg Liothyronine (not converting well from T4 to T3) Was doing ok with ranges of FT4 around 15 -17(12-22), FT3 around 5.2 -5.9 (3.1-6.8) and a suppressed TSH of around 0.1 – 0.005 (0.27-4.2).
Was advised to drop T3 to 5mcg after 4th episode of AFib in October 2023 by A&E doctor and Endocrinology registrar (not my Endo, although same NHS hospital). My Endo was not convinced that I was overmedicated on past test results.
After more AFib episodes (every 3 months) was advised to drop T4 which I did. Subsequent testing showed that my FT4 and FT3 levels have dropped, my TSH is rising and I have the old, well known, symptoms coming back. Weight gain (5kg), hair thinning, brittle nails, carpal tunnel symptoms, lunchtime fatigue, etc.
Between October 23 and April 24 my levels have changed ,
TSH from 0.0035 to 3.05, FT4 from 17.5 to 13.1 FT3 from 5.7 to 3.4
I think the drop in FT3 gives me all the symptoms and I would like to put up the T3 dose.
My endo agrees that I need to put up my hormone replacements but wants me to put up my T4 but I feel, because I have had problems with palpitations ever since I started T4 some 45 years ago and I don’t convert well, I would rather go back on 10mcg T3. I feel my weight, like on several occasions before when I was undermedicated, will go up indefinitely and the TSH will keep going up as well.
Anybody any suggestions which one is better to put up – T4 or T3?
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elkewilliams
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Can you add reference ranges for each test? These are important as they vary between labs.
Did dropping the T3 help your Afib? Low thyrodi hormones are known to be a cause of Afib too.
Have you also been monitoring and supplementing vitamin levels? We need OPTIMAL levels of key vitamins for our thyroid hormone to work well.
Have you recently or could you ask your GP to test levels of ferritin, folate, B12 & D3? Private tests are available, see link for companies offering private blood tests & discount codes, some offer a blood draw service at an extra cost. thyroiduk.org/testing/priva...
There is also a new company offering walk in& mail order blood tests in London, Kent, Sussex & Surrey areas. Check to see if there is a blood test company near you. onedaytests.com/products/ul...
Only do private tests on a Monday or Tuesday to avoid postal delays.
Recommended blood test protocol: Test at 9am (or as close as possible), fasting, last levo dose 24hrs before the blood draw, last T3 dose 8-12 hours before blood draw & no biotin containing supplements for 3-7 days (Biotin can interfere with thyroid blood results as it is used in the testing process).
Testing like this gives consistency in your results and will show stable blood levels of hormone and highest TSH which varies throughout the day. Taking Levo/T3 just prior to blood draw can show a falsely elevated result and your GP/Endo might change your dose incorrectly as a result.
Thank you for your long reply! Following all the advice and reading on this forum every day I have optimal levels of vitamins etc. I see a Nutritionist regularly which helps and test regularly.
All the results of TSH, FT4 and FT3 have the same reference range I gave at the beginning of my message. I still had 2 episodes of AFib, 3 months after each episode, lasting 5 and 3 hours respectively and I am aware that low hormones can trigger AFib as well.
I was told by doctors that I may have to chose to be under medicated and hypo (and feeling under par) if I want to avoid AFib episodes increasing, something I find unacceptable.
Also find that I don’t really tolerate the beta blocker that they gave me (Bisoprolol) and now take it at night to avoid clashing with thyroid hormones which I take in the morning. Can’t avoid the nausea, slight dizziness and feeling unwell too often, though.
The problem with only taking 5mcg T3 is that I can’t split the dose (tablet is 20mcg) for tests.
I am on Henning Sanofi Thybon and Henning Thyroxine which I get from Germany as chemists here won’t dispense the brand. I find it is a good brand and has agreed well with me for years.
It is difficult but possible to split Thybon Henning to 2.5mcgs but obviously wont be very accurate. You could also try delaying your daily dose to tie in 8-12 hours before a blood test as an option.
It looks like you need both T4 & T3 and as you dont convert well then maybe try and get T3 added if you can persuade your Endo.
There are specialist chemists that dispense Thybon Henning in the UK but its probably cheaper to buy in Germany if you hav that option anyway.
This is very interesting. I don’t know if I am rewriting my story because I am getting a bit desperate. However your story rings a bit of a bell for me. Originally I did okish on Levo. My heart rate increased (handleable) at each increase. I thought this was ok because I understood Levo upped my metabolism. However as I was still left with many symptoms at 100 mcgs Levo(some with the edges knocked off - some improvement) I still wanted to be better.
However the introduction of T3 sent my heart into overdrive. Some of the literature seems to imply high T4 levels as opposed to high T3 can be the problem. I never reduced my Levo when I started T3 and I am now wondering (since I still can’t increase my Levo as I am too near the top of range) whether it’s my Levo that is the problem and not the T3!
I asked a question about resistance recently and it’s just your problem seems potentially similar. Paroxysmal A-Fib? I now seem to be suffering SVT (supraventricular tachycardia) which symptom wise is like A-Fib. I have no idea what the difference is.
I will be very interested to see your replies from those much wiser and more experienced than me.
All of a sudden quite a few people on the forum with similar issues.
It is very interesting indeed as I have also found several friends and acquaintances all of a sudden have heart rhythm problems, some of them much younger than I am (72). I also have a diagnosis of SVT as well and as far as I understand the difference is that with SVT you are still in Sinus Rhythm but in AFib your heart beats irregular.
I have had more issues all of a sudden after my 3rd encounter with being COVID positive ( have had all vaccinations and 3x only mild symptoms with COVID, like a cold, hardly any cough).
My Endo didn’t think I had been over medicated but A&E staff only see the TSH and tell you that you are.
I am equally wondering if it is the T4 that is the problem. Reduced my thyroids from October, one step at a time, but still had 2 more episodes of AFib, the last one only lasting 3 hours. So unsure if reducing helped, it certainly sent me into a hypo state.
OK very interesting indeed. I am 71 and had a ‘heart condition’ for many many years. I say heart condition but it’s my belief it’s always been thyroid at the root of it.
That difference between the two very similar heart ‘rhythms’. My husband has one of the many A-Fib conditions but he is unaware of what is happening. He does not even know when he has passed out! Soo that’s how I don’t know enough about A-Fib. I just knew what I was getting was different. Thank you for that info, I never understood the not so subtle difference!
Yes not quite sure what we could be doing about it all. Pity we don’t have thorough research on dosage and some kind of doctor who knew definitively what the hell was going on! Or at least was interested in helping instead of looking at TSH only.
Makes sense to slightly increase your T3 first as you will quickly find out if this is helping (within days rather than months when changing T4 dose) and good levels of fT3 are vital whereas good levels of fT4 for some are not
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Upping T3 - thyroid results advice 
On T3 and T4 has dropped and TSH rose?
On combined t3/t4. FT4 and FT3 at bottom or out of range but increasing the dosage is barely raising the blood test results, TSH suppressed
Should I split my T4 dose? 
