Scary stuff about T4?

With the possibility that I might be taking T4 at some point, I am a little concerned to read that is associated with atrial fibrillation, osteoporosis and thrombosis!! Of course, I understand that this is only when taken in excess, but then what if you HAVE to take "excess" in order to negate symptoms? Some people are apparently taking 200-400mcg so how can they do that without running into difficulties?

Also wondered if anybody knows whether an endocrinologist can test for too much oestrogen - wondering if this might be my problem. Thanks everyone and sorry if this all sounds a bit dramatic!


10 Replies

  • I would think that the AF etc might me due to not being given an optimum of levothyroxine rather than levo itself.

    As far as I understand it, many doctors do not give us an optimum of levo, ie. a dose which makes us well and/or insist anywhere in the range is fine even though symptoms aren't relieved with the dose and usually find relief when the TSH is 1 or less.

  • Thanks, that makes sense :)

  • Long before I was diagnosed my heart played up and I had ECGs etc - heart always fine. Cardiologist puzzled.

    What wasn't fine was my thyroid hormones when eventually discharged from yet another A&E with 'possibly viral with high cholesterol (another symptom) was that my TSH was 100 - blood test never carried out.

    My poor heart was struggling to pump but that was never sussed out by any one of the medical professionals I consulted (paid for) unnecessary op, wrong diagnoses. I could go on and on.

  • Wow! It makes you realize how little understood so many conditions are...what's annoying is they'll have probably made some massive breakthrough in 4 decades time and it'll be irrelevant for us by then! And thanks for the link by the way, very useful. :)

  • Superparrot, It's FT4 and FT3 over range for long periods which increase the risk of AF and osteoporosis. If someone only feels well with sufficient Levothyroxine to elevate FT4 &/or FT3 they have to accept that they may develop adverse health conditions in the future.

    Just because someone is taking 200-400mg Levothyroxine doesn't mean they are overmedicated.

    Endocrinologists can test oestrogen levels.


    I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

  • Thank you very much, that is clearer now :)

  • I have read that under or over treatment of hypothyroidism, by any drug, can be a potential cause of heart issues and high oestrogen (oestrogen dominance) blocks the activity of T3 (the biologically active thyroid hormone, which T4 has to be converted to by the body). So if you have high oestrogen, which a huge proportion of women do, you will have compromised thyroid hormone activity.

    You may be able to have this tested by your doctor?, although I never managed to. But I would personally recommend the use of natural progesterone cream to help balance this problem, if you suspect it.

    There are various articles on the internet about oestrogen dominance and thyroid hormone activity and also a book by Mary Shomon on menopause. The effect of sex hormones on thyroid function is pretty profound so its a problem that essential to address in order to get well.

    Hope this helps


  • Doctors will try to frighten you this way it helps to keep you under their control. There is little to connect heart problems or osteoporosis with thyroxine. If your doctor is worried why does he not send you for tests?

  • How long can you use progesterone?  I stopped my DHEA and progesterone in my early 60's as my doctor was concerned about taking hormones at that age and cancer...

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