Thyroid UK
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Breathlessness and hard heartbeat

Hi all

I have breathlessness and hard heartbeat. This has been ongoing for over a year. Even simple things like walking upstairs and doing general housework makes me breathless and heart beats hard as if I've been running.

I've tried all sorts to rectify this. Upping my t4 & t3 and lowering t3.

I'm currently on 75mcgs t4 and I've reduced t3 from 25mcgs to 20mcgs split 15 and 5.

I had a 7 day heart monitor and all that cane back was "heart rate 62-122 bmp. Patient vomplains of hard heartbeat and breathlessness "

Nothing suggested. No further tests so that was it.

My last thyroid results when on 75mcgs t4 and 25mcgs t3 were:

TSH 0.03(0.35-4.74)

Ft4 11.8(9-19)

Ft3 3.7(2.6-5.7)

Previous to this last result on same doses

TSH <0.03 so lower that this last result

Ft4 11.1 again lower than last result

Ft3 3.9 so higher than last result

I just don't understand how the results have changed when I'd taken the same doses and time between last doses were same to have blood draw.

This hard heartbeat and breathlessness is getting me down.

The hot flushes I complained of before have eased up though I still get them daily since taking Nutri Compose which was recommended to me by a private hormone Dr

Can anyone shed light on why I have hard heartbeat and being breathless

5 Replies

I would say your problem is that you're under-medicated. Your FT3 is under mid-range. Most people need it up the top of the range to feel well.

It doesn't really matter about a couple of 0.1s difference in a blood test - both indicated under-medication. Your FT3 will vary slightly each time because it depends how much you're using up before the test, if you see what I mean. These results aren't fixed, T3 comes into the blood, gets absorbed into the cells, more comes in, more goes out, it varies all the time. Which is why doctor say the don't like using that test (truth is, they just don't know anything about it lol), so it's really nothing to worry about at that level. You just need to get it up over the mid-range level.

Also, breathlessness can be caused by low iron and/or low B12. So, ask for your vit D, vit B12, folate and ferritin to be tested. :)


Hi greygoose

My ferritin was 94 but shot up to 183 after dr gave me iron supplements so I stopped it.

I have a form of blood cancer which means any iron I take will be shifted to ferritin so the cancer can't thrive on the iron.

My bit D was 105 so pretty good.

Folate was 6.4 but I tried using methyfolate as advised on another FB group but it made me extremely anxious.

My B12 was at about 663 but can't remember exactly.

I've now reduced my t3 since last week to just see if it helps stop the hard heartbeat.

Before I knew anything about Ft4 and ft3 I'd only ever had TSH done over the previous 28 years on Levo only and it was always in the high 1's but mostly mid 2's.

I never had these symptoms then. In fact I felt extremely well!!!

So I'm going to Drs tonight to ask to see private cardiologist and if he says it's not heart then I can safely assume it's low fr3??????


I think it's quite likely to be the low FT3, yes. All you can do is increase the FT3 and see if it helps.

1 like

Thank you greygoose


You're welcome. :)


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