Overmedicated? Heart concerns: Sorry, vague. But... - Thyroid UK

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Overmedicated? Heart concerns

pennyrose profile image

Sorry, vague. But I've woke up feeling...anxious? Like how I imagine people feel when they drink too much coffee (I don't drink caffeine, tea sends me loopy).

I was on 70mcg of liothyronine per day, had my annual blood test 3 weeks ago. I thought it would come back under because, regardless of what I do, I'm struggling to lose weight and my eyebrows look a bit thin. Anyhow, it came back:

TSH: 0.03 [0.27 - 4.2]

FT3: 15 (3.1-6.8)

Doctor reduced my meds so I've been reduced back to 60mcg per day and do repeat bloods in 3 months. I should add that I asked if the bloods were high because I took all my meds that morning, 3 hours before the test and she said no. I was just surprised it came back this high.

My problem, and may not be a problem(?) is that my resting heart rate has dropped from 63 to 58 and the past few days it's been dropping to around 49. I only notice it because I get lightheaded and have to take a seat. My blood pressure is a little on the low side so I initially assumed it was that until I spotted the change in my rhr. I haven't increased exercise or fitness levels in the past 2 weeks, the only change has been meds.

Anyhow, like I say I woke up today almost in a state of panic? Heart was racing up at 120 for no reason. As I sit here typing it's back down to 55.

I don't think I've experienced heart flutters/issues before but these past 2 weeks I have.

Sorry...really rambling! I get B12 injections every 3 months (due another at the start of May), and in February they checked my iron levels and they were good (I did have a bit of iron anemia in 2019 but been on top of it since). Haven't checked VitD levels but I've been taking a supplement since I joined this site pretty much.

Not really sure what I'm asking? Maybe about people's heart experiences? I guess it's nothing and will settle down? Thanks all x

17 Replies

Oh dear, next time you take a blood test, don't do it right after you've taken your meds - I think you have a very false reading there, sorry. Do you not spread your lio across the day so you don't have peaks? I was taking mine all at once but now split it following advice on here. I do two doses 8 hours apart but many do three. You should then take your last dose of lio 10 hours or so before you test your blood. Any chance you could ask for a retest?

pennyrose profile image
pennyrose in reply to JAmanda

Thanks lovely. I asked the gp if me taking the dose before my test could have impacted it and she texted back saying no?

When I first started taking lio I split it in 2 but never felt 100%. For whatever reason, 6am pill popping always seemed to work? But maybe I’ll try splitting tomorrow for a couple of weeks and see if there’s improvement x

JAmanda profile image
JAmanda in reply to pennyrose

I really don't think docs understand how lio works. There's plenty of evidence that it peaks around two hours after taking it.

SlowDragon profile image

Suggest you get FULL thyroid and vitamin testing done...making sure you test correctly

That means day before test, split T3 dose into 3 smaller doses at equal 8 hour intervals and make sure last 1/3rd T3 dose is between 8-12 hours before test

When were vitamin levels last tested

What vitamin supplements are you currently taking

As you have Hashimoto’s are you on strictly gluten free diet

For full Thyroid evaluation you need TSH, FT4 and FT3 tested.

EXTREMELY important to test vitamin D, folate, ferritin and B12 at least annually

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .

when on T3, make sure to take last third of daily dose 8-12 hours prior to test, even if this means adjusting time or splitting of dose day before test

Private tests are available as NHS currently rarely tests Ft3 or thyroid antibodies or all relevant vitamins

List of private testing options


Medichecks Thyroid plus antibodies and vitamins


Thriva Thyroid plus antibodies and vitamins By DIY fingerpick test


Thriva also offer just vitamin testing

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins by DIY fingerprick test


If you can get GP to test vitamins and antibodies then cheapest option for just TSH, FT4 and FT3

£29 (via NHS private service ) and 10% off down to £26.10 if go on thyroid uk for code



NHS easy postal kit vitamin D test £29 via


pennyrose profile image
pennyrose in reply to SlowDragon

thank you!

I take iron with vitamin c, high strength vitamin d3. Iron was last tested in Feb and was good (high side of the range).

No strict gluten free diet, however I generally don't have a lot of gluten. I'm technically vegetarian but don't eat bread and have pasta maybe once or twice a month?

B12 doesn't get tested again until August (again, I had a severe dip in b12 in August 2019 and had to get a loading dose again), but I get my 3 monthly injections.

I currently don't split my T3 dose. I used to, years ago, when I first started taking it, but I never felt 100%. For the past 5/6 years I've just had a dose in the morning.

SlowDragon profile image
SlowDragonAdministrator in reply to pennyrose

Even if you don’t normally split T3...you need to do so day before test ...otherwise you get falsely high Ft3...then dose gets reduced

Essential to test vitamin D, folate, ferritin and B12 at least annually

What other vitamin supplements are you currently taking apart from B12 injections

Not only is your doctor ignorant about thyroid, but she lacks common sense. Obviously, if you take your T3 three hours before the blood draw, it's still going to be in the blood. And therefore give a high FT3 reading - especially when taking such a high dose as yours. That is so obvious she must be totally lacking in logic not to see it. Unless, of course, she's just looking for an excuse to reduce your dose.

So, now, you're probably under-medicated. Anxiety is very often a symptom of low T3.

pennyrose profile image
pennyrose in reply to greygoose

Thanks so much. Haven’t felt this way in such a long time! I should’ve skipped my meds. I’ve definitely felt over medicated previously but not this time. In the message she said:“Dear PennyRose,

Thanks for getting back.

The t3 should give a steady state in the blood , so although it may alter the blood test results a little it shouldn't make a big difference.

Hope that helps”

Not sure if I’m dizzy because my heart rate keeps dropping or because of my low blood pressure

greygoose profile image
greygoose in reply to pennyrose

There are many, many causes of dizziness. Could be a bit of both. Low blood pressure is a hypo symptom, so your FT3 could very well be too low.

The t3 should give a steady state in the blood , so although it may alter the blood test results a little it shouldn't make a big difference.

Well, I think that 70 mcg T3 floating round in the blood would make a big difference. It might not if it were just a usually dose of 10/15 mcg. But, I think your doctor is being unrealistic. Trouble is, it's impossible to calculate exactly how much difference it would make. But, if she had any sense, she would do another test under better conditions. Why did you agree to the test, anyway? If you've not long since taken your hormone, it's always better to refuse the test and say you'll do it another day, leaving an 8-12 hour gap from the last dose to the blood draw. :)

pennyrose profile image
pennyrose in reply to greygoose

Ah! I didn’t realise I could/ should refuse blood test? They check it annually and did the test as they were checking my blood pressure (checking it every 3 months). She’s a locum I believe, and I think from chatting to doctors at the practice I’m one of the few that have lio.

helvella profile image
helvellaAdministrator in reply to pennyrose

Drawing blood for a test is an intervention which requires your informed consent. Just like every other intervention (except emergency things).

However, there is a low level of indicating acceptance, holding your arm out is sufficient to be taken as agreeing.

greygoose profile image
greygoose in reply to pennyrose

They can't do anything to you that you don't want done, nor prescribe anything that you don't want to take. I know they think they are all-powerful, but they really aren't! :)

The heart instability and the anxiety are both linked to the sudden drop in available T3 I would expect. I certainly go through a rough patch if I reduce anything.

As everyone else has told you, you should not have done it that way. You are now under-dosed. You need to ring the surgery and explain that you are not happy with the way the blood test was carried out and that you want to repeat it next week and then do it the way it's explained above. You can't hold out for 3 months based on a false high reading.

Thanks so much, I’ll try and make an appointment but my surgery are only making ok the day appointments so have to wait till tomorrow. It’s so odd! Feel highly strung but my heart rate is so low!

SlowDragon profile image
SlowDragonAdministrator in reply to pennyrose

Recommend wearing a Fitbit or equivalent to record resting heart rate and activity levels

pennyrose profile image
pennyrose in reply to SlowDragon

I do, that’s how I know my rhr has dropped this past 2 weeks. This past week I have days where it’s dropping below 50 and it feels noticeable

SlowDragon profile image
SlowDragonAdministrator in reply to pennyrose

So get bloods retested ASAP and dose reinstated

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