Very high heart rate after exertion/exercise - Thyroid UK

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Very high heart rate after exertion/exercise

WitchingHour2point0 profile image

Hi all,

I'm trying to find out why my heart rate goes so high during exercise or exertion. I very recently began running again, and while I acknowledge there is an element of unfitness here I don't think it explains the whole story.

My overnight resting heart rate is now around 60bpm with my sedentary HR about 70bpm.

With even slight exertion such as climbing the stairs, my heart rate goes up to 110bpm.

On a run a couple of weeks ago my HR climbed to over 200bpm. I appreciate that I haven't done any serious cardio work in 3years but I can walk for ages without a problem so I'm not sure it's it's entirely a fitness thing.

Is there a connection with hypothyroidism here?

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WitchingHour2point0 profile image
WitchingHour2point0
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13 Replies
Jaydee1507 profile image
Jaydee1507Administrator

Have you had your ferritin or an iron panel done recently?

Heart rate changes can often be due to low iron/ferritin which is extremely common with hypothyroidism.

You may also not be optimally replaced yet so your heart is working harder than it would normally, plus deconditioning issues.

When hypo we get low stomach acid which means we cannot absorb vitamins well from our food, regardless of a great diet. For thyroid hormone to work well we need OPTIMAL levels of vitamins. Have you recently or could you ask your GP to test levels of ferritin, folate, B12 & D3? Private tests are available, see link for companies offering private blood tests & discount codes, some offer a blood draw service at an extra cost. thyroiduk.org/help-and-supp...

There is also a new company offering walk in (includes free blood draw) & mail order blood tests in London, Kent, Sussex & Surrey areas. Check to see if there is a blood test company near you. onedaytests.com/products/ul...

Only do private tests on a Monday or Tuesday to avoid postal delays.

Do you have a copy of your latest blood results that you can share with us? You are legally entitled to a printed copy of your results, ask at GP reception. In England you can get the NHS app and ask for permission to see your blood results on that by asking at GP’s reception.

WitchingHour2point0 profile image
WitchingHour2point0 in reply toJaydee1507

On 125mcg Levo and 25mcg T3 results were:

TSH: 0.02

FT4: 17.8 (12 - 22)

FT3: 5 (3.1 - 6.8)

previous to that on 125mcg levo and 20mcg T3 were:

TSH: 0.02

FT4: 18.3 (12 - 22)

FT3: 5 (3.1 - 6.8)

In July Vit D was 107 (>50) and ferritin was 98 (13 - 150) but that was actually up from 75 in January.

In January B12 was on the low side at 81 (37.5 - 188), folate below range at 4.9 (8.83 - 60.8) I have been supplementing regularly since then so I'm anticipating they will have improved as they usually do once I'm supplementing. (retesting all next week)

Iron panel looked ok last year. Attached.

Edit to add: I'm late 30's but perimenopausal too. Waiting to start HRT shortly.

iron panel results
Jaydee1507 profile image
Jaydee1507Administrator in reply toWitchingHour2point0

Did you take each thyroid test in the same way? How long before each test did you take levo & T3?

It's just that your FT3 looks like it hasn't moved at all but your FT4 has dropped with the addition of more T3.

Did you feel the benefit of adding more T3 or could it be the additional T3 is causing your heart rate to spike more?

WitchingHour2point0 profile image
WitchingHour2point0 in reply toJaydee1507

Thanks for helping me unpick things! Tests are always done in the same way. I split my dose of t4 & t3 in two. One when I get up, the other around 2:30 in the afternoon.

I test at 7:30 in the morning, so while not as suggested on here they're all done the same way so they're comparable.

I wanted to up the levo after the previous test but private endo said to up t3.

I started levo in summer 2020 and I've never found a stable dose. If I felt ok on a dose and tried to leave it longer than 8 weeks for an increase by 12 weeks I've been symptomatic and bloods have borne out that I needed an increase.

Suspect female hormones are impacting things; Oestrodial below range and FH above range, LH is creeping up to and now 80% through range.

I just worry about my heart rate - when I realised I'd gone above 200bpm I just walked home fearing I'd have a heart attack! Didn't feel that bad in my body though.

Jaydee1507 profile image
Jaydee1507Administrator in reply toWitchingHour2point0

I'm thinking that your original idea to increase levo may have been better, perhaps even only by 12.5mcgs.

WitchingHour2point0 profile image
WitchingHour2point0 in reply toJaydee1507

I'm doing bloods on Monday next week ready for my consultant appointment so I'll have a better view of where I sit next week in terms of dosing. Hoping to start HRT next month so that will change things again.

I'm not yet optimal but I'm not far off, I don't think. I feel great! Certainly compared to where I was in 2020.

I just can't figure out the heart rate thing.

Jaydee1507 profile image
Jaydee1507Administrator in reply toWitchingHour2point0

Was your heart rate doing that though on your lower T3 dose? 25mcgs is a relatively high dose used in a combination.

WitchingHour2point0 profile image
WitchingHour2point0 in reply toJaydee1507

I wasn't actively exercising then but brisk walking taking the dog out would see my HR rise to 140ish!

Buddy195 profile image
Buddy195Administrator

How quickly does your heart recover after exercise? The fitter you become, the shorter this time elapse will be.

Personally, I wouldn’t push yourself to go more than 220 minus your age for any significant period. In a spin class I sometimes push myself, but only for short bursts. I’m also mindful to monitor how long it takes for my heart rate to drop back to my normal range.

As Jaydee1507 has said, it would be useful if you could share your thyroid and key vitamin tests with us.

Be mindful not to over exert yourself; little and often is a good fitness mantra!

WitchingHour2point0 profile image
WitchingHour2point0 in reply toBuddy195

Hi Buddy - I've added my results up thread in reply to Jaydee. :)

It wasn't intentional! I just happened to glance at my watch and realised I'd surpassed 200bpm. It was back to 135ish within 20 minutes.

DippyDame profile image
DippyDame

Without recent thyroid blood test results it's almost impossible to comment, but...

It could be that you are undermedicated and your system does not hold enough hormone to support the extra exertion.

If thyroid hormone level is low ( particularly the active hormone T3) then metabolism is also likely to be slow and if metabolism is slow energy levels and stamina suffer....particularly during endurance type exercise.

As you exercise, your heart contracts faster and increases blood circulation, resulting in oxygenated blood, reaching the muscles more quickly. As the body moves, it requires more oxygen; hence the heart will have to meet the demand by pumping more blood, which increases the heart rate.

The heart needs a great deal of T3 to function well so another reason to have a full thyroid test to include...

TSH, FT4, FT3, vit D, vitB12, folate, ferritin and thyroid antibodies TPO and Tg if not akready tested

Many of us test privately....

thyroiduk.org/help-and-supp...

Until you check and resolve any deficiencies I'd suggest you hold back on strenuous exercise

Listen to your body, it's telling you to slow down

Is there a connection with hypothyroidism here?

Hopefully the above helps answer your question.

WitchingHour2point0 profile image
WitchingHour2point0 in reply toDippyDame

Hi Dippy,

My results are further up thread in reply to Jaydee. :)

DippyDame profile image
DippyDame in reply toWitchingHour2point0

Did you leave a 24 hour gap between last dose of levo and the test, and ditto a 12 hour gap for T3

Did you test at least an hour away from food and drink?

Were you on a steady hormone dose for at least 6 weeks before testing?

Sorry if I've missed that somewhere!

T3 will normally cause FT4 and TSH to drop

Dropping T3 by 5mcg has made little significant difference.

I think we need to reserve judgement until we have new labs with testing done according to protocol described

Don't worry....just don't overdo things meantime.

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