Underactive with overactive symptoms

I have felt unwell for a few weeks . I've been on thyroxine since 2002 . I nearly collapsed at the wheel at work , which felt like a panic attack (never had one before) . Heart was racing , flushed , faint . This went on for an hour . Doctor has upped my thyroxine to 125mcg . I've gone low before but never had these symptoms . I've lost weight , eat like a horse , felt full of energy . I found this strange . I'm now waiting for an urgent cardiology appointment as doctor says my heart palpitations are not related . Has any one else had this problem ?

7 Replies

  • Hi Claire, have you had recent blood tests that show you are underactive? As you say your symptoms sound more like overactive. Do you have any other symptoms of over-medication? Check the patient information leaflet for a list of symptoms. What dose did you go up from? Maybe you need to increase it more slowly, say taking the higher dose on alternative days. Sometimes I get hot-headed, light-headed, foggy-brained and palpitations about an hour after taking thyroxine and it can last for an hour or more.

    I had blood tests that showed things were pretty much in balance and then within 3 weeks had an episode of over-medication symptoms; I dropped my thyroxine to 75mcg. (I was on 100mcg/75mcg on alternative days) and after about 3 to 4 weeks have gone back to normal. I've still to see GP - couldn't get an appointment for over 4 weeks but want to see my own GP and not another one.

    Getting your heart checked is no bad thing. I had a 48 hour monitoring done last year and it all came back OK, so reassuring.

    Hope you find an answer. Liz

  • I've been on 100mcg for years no problem . Doctor told me yesterday that's it's low . Hence the increase to 125mcg which I've started this morning . . I can't think what has caused it . Strange . Thank you for your reply .

    Claire .

  • Heart palpitations are one of the main symptoms of thyroid/adrenal problems. In fact a) I think you will find most people here have them and b) (personal experience) cardiologists know that, even if GPs and endos apparently don't.

    The key is - are you over or under active and do you have adrenal problems? All cause heart palps and fibrillation. Testing is the way to find out. Get your doctor to do fresh TSH/T4/FT3 tests. Insist if necessary.

    Also, without being indelicate, how old are you? Your ovaries and sex hormones are part of you endocrine system and can cause those symptoms of things are changing.

  • I'm 38 . And had my blood test on Monday . . I have read on the internet about palpitations . I'm just a little concerned as I've never had these affects whilst being low . I have been told not to drive for three weeks whilst I'm under investigation . And I do a driving job . Which is great .


  • I've been underactive since 2002 . When radiotherapy killed my thyroid . No other problems . I've been eating a lot of couscous lately . Would that affect it ? I know certain food groups can .


  • Hi Claire, check the list on the Thyroid UK webpages on list of symptoms. thyroiduk.org.uk/tuk/about_...

    You will see some your symptoms are indeed underactive related. Maybe you need as Rosetrees suggests to get more blood tests including T3. Maybe you need to take T3 as well as T4, like many other contributors to this site do.

  • I will definately look into that . . And thank you very much for all your comments . It's nice to speak to people who know what I'm on about . .


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