Can being overmedicated cause atrial fibrillation?

[MissDemeanour191]

Hi can I get some advice please? GP thinks my Levo should be lowered from 125mcg to 100mcg as my TSH is now at 0.097. T3 5.6 and T4 12.9. Was really surprised tested T3, didn't think they did it! Never been offered before, have had to use Medichecks.Had my bloods done 2 months ago ( july 2023) and TSH was 0.125 T4 17.4 no T3 as was at GP surgery. My T3 results from Medichecks have been around 3 or 4 in past. So was pleased is now up to 5.6 don't know what i'm doing better! But have relaxed intermittent fasting do know food is needed to help conversion.My question is: should I let GP lower my dose? Can being overmedicated for long period and really low TSH potentially lead to heart problems in the future? Many Thanks.

[SlowDragon Administrator]

TSH is now at 0.097. T3 5.6 and T4 12.9.

Please add ranges on these

Was test done early morning, ideally just before 9 am, only water to drink between waking and test and last dose levothyroxine 24 hours before test

Are you only taking levothyroxine….no T3?

What are your most recent vitamin D, folate, ferritin and B12 results

[MissDemeanour191 in reply to SlowDragon]

Hi I took levo in morning before appt, as went to GP for something else, so didn't know she was going to do blood for thyroid!I will have had coffee before 9am appt but no food, and yes, coffee couple hours after took levo.

I take vit D & B12 daily. But haven't tested recently. Same for folate/ferritin.

Main concern is potential heart problems if I carry on with 125mcg. I did think TSH should be below 1 for us to feel 'normal?'

[SlowDragon Administrator in reply to MissDemeanour191]

what’s the range on Ft4 result

Ft4 looks very low, especially as you took levothyroxine before blood test

Roughly how many hours before test?

Suggest you get vitamin levels tested next

[Singwell in reply to MissDemeanour191]

Did your GP take your pulse or do an ECG? how can such a statement be substantiated?

[tattybogle]

Hi MissDemeanor, lots of useful stuff on the subject of low TSH /RISK collected here :

healthunlocked.com/thyroidu... useful-evidence-that-tsh-between-0.04-0.4-has-no-increased-risk-to-patients-on-levothyroxine-updated-new-study-does-show-small-risk

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Yes overmedication and hyperthyroidism do lead to increased risks of heart problems. However TSH in isolation is not the right way to tell if a patient is overmedicated.

Low TSH and overmedication are not necessarily the same thing , ...the true meaning of overmedication is 'thyroid hormone levels are too high' ...... if you have no symptoms of 'too much thyroid hormone' and T4 / T3 are within the 95% population ref range , then you are not 'really' overmedicated .

TSH reads a bit different once we take Levo but most GP haven't realised this yet, On levo TSH is 'relatively' lower/ fT4 is 'relatively' higher than before , so some patients do get a below range TSH when on the right dose of levo and are not overmedicated ... details to baffle GP with here : healthunlocked.com/thyroidu.... tsh-is-just-the-opinion-of-your-pituitary-about-your-dose-but-your-pituitarys-opinion-is-a-bit-warped-once-you-take-thyroid-hormone.

[greygoose]

Long-term over-medication - i.e. very high over-range FT3 - can increase your risk of heart problems. A low TSH with in-range FT3 cannot. The TSH has nothing to do with hearts.

So, if you feel good, don't let your GP reduce your dose! Or you won't feel good any longer.

[Singwell in reply to greygoose]

I agree with this, although we do know that hypothyroidism and hyperthyroidism are linked to heart Arrythmia.

[greygoose in reply to Singwell]

Yes, of course we do. But the link is the T3, not the TSH.

[Singwell in reply to greygoose]

That I didn't know! Thanks for clarifying. The GP appears confused to me. Needless to say, no-one measured my T3 even back in 2015 and I had to insist when I started my thyroid healing journey last December. And even then the labs won't do it - my GP had to request it as a sole test before they'd do it. They see the T4 and TSH and don't bother if those are 'significant'. GP told me herself. Who's in charge of our health one wonders? Anyway, grateful for this forum as I personally feel a lot better.

[greygoose in reply to Singwell]

Quite honestly the lab is in charge. They decide what they will test and what they won't, regardless of what the doctor orders.

But, doctors don't understand the results of T3 testing, anyway. It would just be for your benefit.

[Singwell]

This seems odd to me. Hypothyroidism is linked to AF and almost certainly led to me developing it after being subclinical hypothyroid for 5 years and - stupidly- making the decision not to have it treated. Last December- in remission now for AF - I embarked on medication to treat my hypothyroidism. We had to go really slowly because as soon as my metabolic rate started to change with the levothyroxine I started getting palpitations and high heart rates. My GP said this was a clinically significant side effect and to stay on a half dose of 12.5mcg. I'm now up to 62.5 and doing well - we think I'll need to slowly increase to 75 or thereabouts.

Honestly- I think your GP is confused. Whilst hyperthyroidism can also lead to high HR and AF, the levothyroxine as such isn't the cause. There's no single known cause of AF anyway.

So my question is - are you getting palpitations or arrhythmia at all? Or is this something that you're GP is waving as a red flag?