High heart rate from reducing T4/reduced heart rate from increasing T4

[Wired123]

This is my second post on the same subject as I didn’t get the answer I needed so am asking the question in a slightly different way.

I’d be keen to hear if anyone has experienced an increase in heart rate from reducing their T4 and/or the opposite effect of a drop in heart rate from increasing T4.

The reason I ask is that my HR seemed to go up when I reduced my T4 and now my Endo has asked me to go back to my original dose of T4 because of this. It seeks counter intuitive but wanted to see if anyone on this forum has any experience of this.

[Lotika]

No - they’re messing with my combo of T4 and T3 but HR, according to FatBut, remains exactly the same... and they cut my T4 in half to accommodate T3.

[Jazzw]

Yes. A higher heart rate can be a feature of undertreated hypothyroidism. I know that sounds counter-intuitive and I’ll admit to not understanding quite why it should be—perhaps it’s just as simple as, when you’re adequately replaced, your body doesn’t have to work so hard. I’ve also had reduced blood pressure with optimal thyroid hormone replacement.

[jrbarnes in reply to Jazzw]

Possibly, if a person reduces their T4 and doesn't replace it with enough T3 this could cause a higher heart rate because of undertreatment?

[De8813]

Hi Dk123 I had my levo reduced in October 😖 I wear a sports watch and noticed my heart rate went up from 54 beats to around 63. I was very surprised at this expected the opposite. Tried to get Dr to put me back on original dose, but no said retest tsh in 3 months. Going this week.

[Wired123 in reply to De8813]

That’s all these doctors know “TSH”! It’s not the be all and end all.

[Popoff]

Yes it is possible for the heart rate to go up when reducing T4. One way this could happen is with the reduction of T4 from the levels that your body needs or it is used to, the cortisol levels may go up to compensate the reduction in T4 and this causes stress to your system and hence higher HR. Is there a good reason for wanting to reduce your T4? If you need to do so, try to reduce it in gradually and in small doses, eg. 12.5 mg at a. time. Good luck and hope that this helps.

[Hookie01]

Yes this happens to me, noticed it when I changed brands to Mercury Pharma. My hr goes very low now.

[Mistydeb01]

According to my Apple Watch, my heart rate fluctuates so much day to day. About 4/5 times a week my heart rates drops to 44/45 and then doubles a few minutes later. Don’t think I’m anywhere near optimally medicated yet as I’m still working on my vitamin levels

[Wired123 in reply to Mistydeb01]

Interesting. Has this been caused by a recent change in meds? My HR was quite stable on T4 only, then it started getting erratic when I introduced T3.

[Mistydeb01 in reply to Wired123]

I’ve started to take metavive 1 since Xmas, only one tablet a day for now, but my HR has had some low points and erratic behaviour before that. I’m only on 50mcg of levo and it took me nearly three years to get increase to that. I’m hope it to get private T3 testing done at the end of the month. I had thyroid and gluten done a couple of months ago by GP. No antibodies for gluten or Thyroid, yet I’m intolerant/ very sensitive to gluten now and have gone free of it (apart from the odd mistake) since the last blood test. My TSH was 0.68 (0.40 - 4.50) and T4 was 12.8 (7.0-17.0), so I’ve got no chance of Levo increase with GP. Thought I’d try the metavive as it’s likely my T3 is still rubbish.