Thyroid UK
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Chest pain when running

I'm a runner and used to run several times a week before I was diagnosed hypothyroid. My latest results are

Tsh suppressed

Ft4 18.4 (10-20)

I have started to get a pain where my heart is when running my usual pace. It stops when I run very slowly. Does this indicate that I should reduce dose or could it be the hypothyroidism and maybe I need an increase?

9 Replies

Putting TSH suppressed instead of a result with a range, and not having a Ft3 result means it is impossible for other posters to guess what is the issue could be.

I strongly suggest you have your Ft3 tested to see if you are converting T4 to T3. If the NHS refuses to do it for you then you have to do it privately.

In addition as you are a runner you should get your iron (ferritin and if possible haemoglobin), vitamin B12, folate and vitamin D levels tested.

Oh and if you have not had your thyroid peroxidase antibodies checked then get them done. Again you may have to do all these privately via either Blue Horizon or Medichecks -


Tsh 0.05

Don't have a Ft3 and my vitamins are optimal in latest test.

Tpo 42 (<60)


The active thyroid hormone is T3 and if you don't have a test result but want to continue to be at optimal health and run then you need to do private tests to see if you are converting T4 to T3 adequately and that your FT3 level is high enough but not too high.


Do you take NDT or levo? And do you have a t3 result. I run and don't get any chest pain , I would get it checked out to be safe




When we are hypothyroid and exercise, it can reduce our T3. Levothyroxine is T4 only and converts to T3. If by exercising before we are on an optimum dose (usually FT4 and FT3 should be towards the upper part of the range) we can reduce our T3.

T3 is the only active hormone required in all of our receptor cells. T4 is inactive and has to convert), so you may be reducing your T3 inadvertently which is causing pain. I'd get your doctor to check your heart anyway.


Very low iron is incredibly debilitating and when severe enough it can cause terrible chest pain.

Low T3 will cause lots of chest pain too.

Ask your doctor to check your iron, vitamin B12 and folate levels. Throw vitamin D into your request to. Get copies of your results and reference ranges and post them on here in a new post and ask for feedback.

I think it is unlikely you will persuade the NHS to test your Free T3, but you might be lucky. I suspect either the lab will refuse to test or your GP will refuse to ask for it.

1 like

I am a runner too and I got chest pain when my dose was too high - also found it harder to run because I couldn't get my breath properly. Personally, I have learnt from experience that a TSH of 0.05 would be too low for me. My FT3 never changes whatever dose/type of medication (I gave T3 a good go) I'm on, so for me TSH does help me to know what's going on.


PS ask your doc to check your ticker out to be sure all is ok


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