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Daily bouts of heart palpitations due to low thyroid!

Hello all,

I just signed up as I really need some advice and help, if possible.

Just a quick summary of the events that had led to the current problem:

-stage 4 endometriosis, 1 laparoscopic surgery, no troubles conceiving;

-no thyroid problems prior to first pregnancy in 2013;

-started getting numerous palpitations daily from week 13 till week 19 of first pregnancy, 22 palpitations a minute, or 1 palpitation per every 3rd beat, lasting for a couple of hours a day, every day.

My OB and GB attributed these palpitations to stress and brushed the problem off. -palpitations gradually subsided and consequently stopped by week 20 of first pregnancy.

- 14 months after the birth of my son, I started to get this palpitations again.

My heart would start pounding as soon as I would open my eyes in the morning.

-had been suffering from them for one year, every day, till I became pregnant again and doctors drew blood to check my TSH level, which turned out to be 3.

I was immediately put on levothyroxine and surprise, surprise!!! My palpitations stopped as soon as I started therapy.

-after the birth of my daughter in July this year I gradually decreased from 50 to 25 mcg levothyroxine only for the palpitations to come back with a vengeance. Then I stopped taking the medication for 3 weeks.

-currently, I am on 50 mcg, started taking it from the 1st of October.

Alas, the palpitations have not gone completely away. They have really subsided. From 15000 PVCs daily (holter result) they reached 50 when on levothyroxine.

Last few days are again really a challenge since I started getting at least 300 palpitations daily although I am on levothyroxine 50 mcg.

Don't know yet what my TSH level is since I've been on levo for only 28 days.

I am desperate since previously 50 mcg levo did the trick and made my palpitations disappear completely.

Endocrinologist doesn't acknowledge the connection between palps, thyroid, and levothyroxine intake. Neither does my GP. They say it is a coincidence that my palpitations stop altogether when I am on thyroid medication.

Any advice or help is greatly appreciated!

I have a 3 year old and a 4 month old to look after.

Can't take these daily bouts of thousands of palpitations anymore!

- no Hashimoto's, no antibiodies, ultrasound of thyroid looks fine. Doctors don't know where this TSH of 3 comes from. Suggest it might be due to high estrogen levels (endometriosis).

Thank you in advance!

I am not from UK btw. Just to let you know that since we might use different reference ranges for FT3 and FT4 (mine are in the normal range), and different types of thyroid medications.

6 Replies

To you have results for FT4 and FT3? If so, post them, with the ranges. Doesn't matter if the ranges are different, the results are interpreted according to the range of the laboratory that did the test.

TSH is a very bad indicator of thyroid status. Your FT3 could be very low, even with a TSH of only 3. And low FT3 can cause palpitations. :)


Thank you for your reply, Greygoose!

My FT3 during the pregnancy with my daughter was 4.9 (at the very beginning of pregnancy, with TSH 3, and on no Levo, daily palpitations), then it has been constantly decreasing to reach 3.40, and then it went up to 4.10, 4.15, 4.20, 4.30 at the end of pregnancy (lab ranges are 3.10-6.80).

FT4 has moved from 17 (beginning of pregnancy) to 13, back to 16 at the end of pregnancy (lab ranges for FT4 are 12-22).

TSH during pregnancy has ranged from 3 to 0.8, to 2.3 at most.

During that pregnancy I had palps only when decreasing the dose of Levothyroxine, FT3 at that time was about 4.1.

With the lowest FT3 of 3.4 I had no palpitations whatsoever because I had not decreased the dose of Levo at that time...

That's really a mystery to me.

It seems that my palps are resolved only when I am on Levothyroxine.

I gave birth in July this year, had no palps postpartum... until I lowered Levo to 25mcg... Still they were not so numerous.

I stopped Levo completely, 2 weeks after stopping it, my TSH was 1.6, FT4 15, FT3 4.5, about 50-60 palps daily.

2 more weeks later, in the middle of September, palpitations became unbearable (thousands a day, lasting all day long), I assumed TSH must have been on the rise.

I resumed 50 mcg Levo intake on the 1st of October, felt major improvement immediately, palpitations have not gone completely away. However, they were reduced to 20-50 daily.

With the beginning of my period last week they considerably increased in number and currently they amount to 300-400 a day perhaps.

I am going to check my TSH, FT3 and FT4 levels this next week.

As you can see it seems that palpitations depend on Levothyroxine intake and not so much on FT3 levels.

At least that's the conclusion I can draw by looking at my labs throughout pregnancy and postpartum.

This whole thing is so weird...

I am desperate to find a solution to the problem. I am only 32, can't live like this... :( It's not normal at all.

I have an appointment with a cardiologist in January next year to determine whether I need an ablation or not.


Well, you can't really compare the way you were when you were pregnant with the way you are now. So many hormones come into play during pregnancy. We need to concentrate on now.

However, I see that your FT3 has never risen above mid-range. Where as most people need it up the top of the range to be well. The FT3 is the most important number. But we do need the FT4 to determine whether you are converting properly. A bit difficult to tell with the numbers all jumbled up like that, but as the FT4 never goes above mid-range either, I would say you're conversion is adequate. But, you are under-medicated.

If you cannot increase your dose enough to raise your T3, it could be that you have nutritional deficiencies. If I were you, I would ask your doctor to test your vit D, vit B12, folate and ferritin. These all need to be optimal for your body to be able to use the hormone you're giving it.

Optimal is about 100 for vit D; over 500 for B12, and at least mid-range for folate and ferritin. If yours are below these levels, then you need to supplement them. :)


Welcome to our forum and I will disagree with both Endo and Doctor I had palpitations before being diagnosed due to a very high TSH (no one ever did a blood test) and they also continued when on levothyroxine.

Your dose should be raised by 25mcg of levo every six weeks until you feel much better. Forget the TSH as it's not that important after being diagnosed, you are hypothyroid and you will be for life.

Your dose of 50mcg is probably too low yet for your heart to be able to pump blood efficiently. It should improve as the increase your dose.

Once diagnosed as hypothyroidism we have it for life and it is a life-long condition.

Thyroid hormones, T3 in particular, is the only Active thyroid hormone and levothyroxine (T4) should convert to sufficient. If not, we wont feel well. Our FT3 should be towards the highest part of the range, not middle or low.

More damage is done by trying to keep the TSH somewhere in the range but 1 or lower we feel best. Levothyroxine drives our whole metabolism from head to toe and nothing works well without sufficient, heart in particular.

Your next blood test should be the very earliest possible and fasting although can drink water. Allow 24 hours gap between your last dose of levo and the test and take afterwards.

Always get a print-out for your own use, with the ranges, and post for comments.

(I am not medically qualified.


Hello again and thank you so much for your precious advice! I see light at the end of the tunnel now.

Maybe I need some FT3 intake as well, but as Greygoose suggested I don't seem to have any problems with FT4/FT3 conversion. Moreover, if I want to take some FT3 I will have to purchase it from Greece or Turkey and without a prescription (Endo and GP think it's my nerves playing tricks on me!!!) I doubt I will manage to get it.

I want to make another summary of some events and labs:

-2013 - during first pregnancy I was having these palpitations from week 13 to week 19. No doctor checked my thyroid levels back then.

- week 30 of first pregnancy I decided to go to a lab to check my levels just to see where I was at since I had been reading all this information online about how important thyroid levels are.

My levels at 30 weeks pregnant were as follows:

TSH - 0.8, FT3 2.5 (3.10-6.80), FT4 12.5 (12-22).

I had no palpitations whatsoever, not on Levo, that was the first time I had ever had my thyroid levels checked.

Levels 2 weeks later, at 32 weeks:

TSH 2.3, FT3 3.40 (3.10-6.80), FT4 14 (12-22).

Showed them to my OB and my GP, they said they were fine. I believed them and got this whole thing off my mind.

Now, being already familiar with thyroid conditions and levels, I can see I was hypo back then, at 30 weeks pregnant... Had no palpitations back then, however.

- 2013 October gave birth to my son;

- 2014 December - daily palpitations from 13-19 weeks of first pregnancy came back.

I knew something must be wrong so I went to a lab to have my thyroid and estrogen, progesterone, FSH, LH, and so on, levels checked.

I must say that no doctor at that time deemed this necessary so I went to a lab and decided what levels to check all by myself.

Here, in my country, we can do that as much as we please.

-2014 December my labs were:

TSH 3.35, FT3 5.83 (3.10-6.80), FT4 20.10 (12-22), not on Levo, daily palpitations up to 50-60 a day.

-2015 February:

TSH 4.30, FT3 5.11, FT4 15.70 - already experiencing severe palpitations

Endo said ultrasound of thyroid looked fine, no explanation where this TSH came from. Ascribed palpitations to stress.

- 2015 April - palps became really, really unbearable, lasting 24/7, couldn't even sleep well.

-2015 May - laparoscopic surgery due to stage 4 endometriosis.

Palpitations went completely away the day after surgery.

Had my levels checked 2 weeks after surgery:

TSH 1.6, FT3 6.5 (3.10-6.80), FT4 18.65 (12-22) - no palpitations

Palpitations came back in mid-June 2015 .

I have not tested my thyroid levels anymore, doctors managed to convince me somehow my palps are stress-induced.

- 2015 October: got a BFP, still experiencing daily palps, convinced my GP and OB to check my TSH, FT4, FT3 as I sensed I might have an underlying condition and the labs were as follows: TSH 3, FT3 4.60 (3.10-6.80), FT4 17 (12-22).

Was put on 50mcg Levo, being 5 weeks pregnant, palpitations went away immediately.

You are familiar with the rest!

By looking at the results I can see that I had no palps only when on Levo (during second pregnancy) or with a level of FT3 above 6, on no Levo (after my laparoscopy in May 2015).

There are couple of things I cannot figure out:

How come I had no palps in week 30 and week 32 of my first pregnancy when my FT3 level was dangerously low (2.50 and 3.40)?

How come I had severe palps in December 2014 and February 2015 with an FT3 of 5.83 and 5.11?

Is it because thyroid, or rather my body or heart, had been deprived of FT3 long enough to already feel the need for this hormone and to start experiencing palpitations?

Now, a couple of words about supplementing:

Week 21 of second pregnancy, March 2016; my OB wanted to check my iron, D3, B12 levels.

It turned out I am severely D3 deficient.

My labs were as follows:

21 weeks pregnant, March 2016:

iron - 26 (ranges: 7-26),

B12 - 215 (ranges: 140-490),

D3 -21 (ranges: 50-120).

I assume these levels must be lower in pregnancy. Still, pregnant or not, I am D3 deficient.

I started taking B12 1000 mcg shots, and about 4000 IU D3 daily.

However, I experienced an adverse reaction to D3 and B12 injections.

D3 alone induced mild diarrhea but strong anxiety, felt jittery all day long, was not able to sleep at all, thought I was going crazy.

B12 intake resulted in severe diarrhea, vomiting and dehydration. I was not able to keep anything down, even water, for 24 hours after B12 injection application.

I was 22 weeks pregnant and decided not to run the risk anymore. Stopped all kinds of supplements.

I managed to up my levels to: B12 - 300 (140-490), D3 - 35 (50-120)

Now, I intend on testing not only TSH, FT4, FT3, but also selenium, folate, ferritin, iron (Is ferritin same as iron?), B12, D3, iodine (problably?)

Can I supplement KELP by the way?

I intend starting supplementing slowly, low doses of D3 and B12, no B12 injections!

The weirdest thing is that I've got 4 friends with no thyroid condition, NO endometriosis, however, whose labs are worse than mine:

I have the highest iron level, highest B12, and believe it or not, the highest D3 of them all. They are all severely deficient in B12 (at least I am not deficient in it), their iron is mid-range, and, to top it all, their FT3 and FT4 are lower than mine being at their worst now.

Their TSHs range in between 1.5 - 2.3.

They have no hypo symptoms, as I mentioned - no thyroid condition, 2 of them are even pregnant now, the other 2 are not.

I advised them to have their levels checked.

I told them these are not optimal levels but nobody pays attention to what I say...

How on earth with labs like these (far from optimal, but still much better than my friends') I experience these terrible daily bouts of palpitations... apparently hypo symptoms...

Could it be my endometriosis suppressing the thyroid?

Why I had no palps at FT3 of 3.40 during second pregnancy (on Levo 50, 50, 25), and now I do have more and more palps even though on Levo 50mcg, with a higher level of FT3?

Isn't Levo intake requirement (thyroid requirements) higher during pregnancy? I thought I would be decreasing my dose postpartum, it turns out I have to increase it...

I am sorry for this long post! I really, really need to bring everything under control. Will not be able to endure being plagued by palpitations much longer. :(


Hello guys!

This time I promise I'll be as brief as possible.

Thank you so much for clarifying the relationship between low FT3 levels and hypo.

I browsed through all my labs (those done before and after pregnancy, NOt during it) and it turned out that I do NOT have any palpitations (i.e. I am not hypo) only at FT3 levels above 6 (reference range 3.10-6.80 or 2.80-7.10 at some labs).

Now, even on 75 Levo my FT3 level does NOT budge at all. I can officially sat I am a bad convertor now, which was not the case 2 months ago:

03 September 2016 - on NO Levo: TSH: 1.64, FT4 15.11 (12-22), FT3 4.69 (3.10-6.80)

09 November 2016 - on 50 Levo for 30 days and 50, 75 for the last 10: TSH 0.55, FT4 19.30 (12-22), FT3 4.99 (3.10-6.80)

I need to add some T3 in the mix, that's pretty obvious!

Endos here won't prescribe T3! Keep telling me my problems stem from nerves.

It's becoming more and more debilitating to live with so many palpitations, which is only one symptom of being hypo (I also experience hair loss and brittle nails).

I think my adrenals might suffer as well since they produce more adrenaline to keep my metabolism going at a normal speed while my thyroid is slowing it down. That's where the palpitations come from: too much adrenaline.

I have another question since you are more into thyroid stuff than I am.

My thyroid ultrasound is absolutely NORMAL, no antibiodies.... Endos don't know where my need to take Levo comes from.

Have you, by any chance, got any idea as to where to look for a problem?

Got stage 4 endometriosis which suggests estrogen dominance or progesterone deficiency.

Have you heard of any other cases where an otherwise healthy thyroid is being suppressed by too much estrogen?

Or do you thing the problem stems from my thyroid?

Doctors won't give answers that's why I turn to you.

I have vitamin D deficiency 48 (50-120), vitamin B12 is mid-range, ferritin is on the low side, within range though. Iron and folate are OK.

Thank you!


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