Is my heart rate too high? Link to hypothyroidism

[CalIie]

Hello!

I am hoping for someone with medical insight, as my GP has been a bit naff...

Background: I have congenital hypothyroidism. In August my heart rate was 130 - 140 bpm at rest. GP ordered bloods, which showed my TSH levels were slightly elevated. My dose was reduced from 150 mcg to 100 mcg (lowest dose I can ever remember having). My TSH is now on the lower side of normal.

My apple watch shows my average resting heart rate is 108 bpm.

Sometimes it is below 100, but most days it is consistently higher and I get alerts from my watch. I put on a bit of weight so want to start up jogging. However, it reaches over 200 bpm after less than 1 minute. Is this safe?

My GP does not seem concerned and says he does not think I would benefit from an ECG. He says it is down to my medication. My mother and SIL are both nurses and are pushing me to go back to my GP to demand an ECG. I am reluctant to do - I have spoken to him twice before, and he makes me feel like I am an overreacting hypochondriac who is wasting his time.

I am 24, 63KG and 167cm. I used to be very sporty!

If you read my ramblings, then thank you very much! :)

That RHR is incredibly high at your age and weight.
For comparson, I am on a similar dose of levothyroxine - 125mcg daily and my RHR is usually 65 when I'm fit and active and about 75 when I'm being a lazy bum and not exercising and drinking (like now!)
I am 170cm and about 80kg.
When my hypothyroidism was undiagnosed and untreated, I would regularly exceed 200bpm at gym, and then go faint and light-headed and dizzy and have to sit down. Once I started treatment and explained this experience with exercise, I was warned by GP NOT to over-exert myself until it was under control.

@NellyDElephant Thanks for sharing your experience :). May I ask what your heart rate is now when you exercise and did your GP ever order an ECG?

See another GP. A resting heart rate over 100 needs investigating.

Your post is a bit confusing "Background: I have congenital hypothyroidism. In August my heart rate was 130 - 140 bpm at rest. GP ordered bloods, which showed my TSH levels were slightly elevated. My dose was reduced from 150 mcg to 100 mcg (lowest dose I can ever remember having). My TSH is now on the lower side of normal."

High heart rate is usually caused by over medication. In that case, your TSH would be very low or suppressed. However you have said your TSH was too high. This suggest UNDER medication so unclear why GP reduced your dose if your TSH was too high?? Have you got your TSH levels the wrong way around? If not the GP should never have reduced your levo and should have investigated a different cause for the high heart rate.

Also is your GP just going off TSH. This isn't always enough to properly diagnose a thyroid issue. I would be pushing for FT4 at least to be measured also. But ideally FT3 as well (you may have to have this done privately as many labs refuse to test FT3 even if it's requested by the GP unless your TSH is suppressed).

Are you having any other symptoms of being overactive, or is it just the high heart rate?

When I exercise somewhere between 140-150 and recovery pretty quick - back down to 75-80 before long at all.
Ive only had one ECG, straight after childbirth - they thought I had MRSA as my heart rate was so high - they said it all appeared normal, but obviously they didn’t twig that the high heart rate was caused by hypothyroidism at that point, and it was a few months later, when a GP spotted and pointed out a goitre on my neck, that blood tests were done and diagnosis made etc

I'm confused too, if TSH was high I don't think Gp should have reduced your thyroxine. TSH is thyroid stimulating hormone, its job is to stimulate the thyroid to produce more thyroxine, when levels are low. Probably worth going back to gp or asking for another opinion.

@TooManyPJs Hi, sorry I got the TSH the wrong way round! Thanks for your detailed post.

So, I was slightly overmedicated in the summer, but my current levels are within normal range but closer to hypothyroidism rather than hyper.

I don’t have any other symptoms of hyperthyroidism. If anything, I would say I have symptoms of hypothyroidism - putting on weight (heaviest I’ve ever been), chronic fatigue, extremely dry skin (might just be winter tbf) etc.

Yes I agree that sounds like you’re hypo. What’s your TSH? Most people who are hypothyroid and on medication don’t feel well unless their TSH is under 1. 150 to 100 is also a huge drop. Usually you increase or decrease 25mcg at a time. I think you need a retest, and likely an increase. I’d also want my FT4 and FT3 tested. Make sure you are getting your thyroid blood tests early morning (before 9) and on an empty stomach. Last levo should be taken 24 hrs before. No supplements containing biotin for a week before the test.

Could be something else causing the high heart rate. It definitely needs investigating. Whenever I’ve had a high heart rate I’ve had an ECG and various bloods. First time it happened I had a referral to cardio for investigation. They test all sorts. I’d see a different GP request an ECG and push for a cardio referral.

@TooManyPJs Thanks for getting back to me :)

I’ve no idea what my levels actually are. I’ve had treatment for hypothyroidism since I was just a few days old and they’ve never told me my actual levels, just whether I am within normal range or not. I assumed this was normal…

I think it would be good to get a long term history of my levels to see what they’ve been like. I find my GP really patronising, so hate talking to him. Will see if I can get a second opinion elsewhere.

Thanks again!