40 years or more on thyroxine

Just wondering how many people on here have taken only t4 for more than 40 years....I am due to have some tests for muscle fatigue that endocrinologist is unsure of cause but as he has never treated someone on t4 for over 40 as drug only been out 50 years and long term effect has not been ruled out, although he is keen to rule it out.


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20 Replies

  • Auntyp62 Me! I was eventually diagnosed in 1975 and have been on Levo ever since, so 42 years.

    Long term effects? Goodness knows! Factor in the aging process and the health problems that brings as things wear out then it's hard to say.

    I introduced T3 about 18 months ago (self sourced, GP doesn't know and I will keep it that way because of her obsession about dosing by TSH and disregarding how you feel) and am still trying to find the perfect dose that makes me well.

    During all my investigations (tests) to find out why I was still very symptomatic on a quite high dose of Levo, I discovered severe Vit D Deficiency, very low ferritin and folate, and almost non existent sex hormones. Also, long term highish dose of Levo gave me high/over range FT4 which I believe led to reverse T3. I couldn't get tested for that at the time, but testing a year or so after adding T3 amd my rT3 was top of range. This obviously all played a part in how I felt, but no idea what caused them so can't blame Levo without any proof (apart from the high rT3).

  • That sounds just like me...always been symptomatic and frequently overmedicated.and high rt3 (which doctors take no notice of)...had vit D issues and B12 but all sorted......still very low energy and sleeping a lot. 3 months ago I got so fed up with it I went privately to a recommended endomcrinologist who discovered my large muscles in arms were very weak and now off to have muscle tests tomorrow...all an elimination process but at least endo is trying to find an answer and believed me when I said I sleep such a lot, something I feel my gp did not believe.....I just wonder if many years of overmedicating can cause muscle weakness....just looking for answers

  • Have you had your Free T4 and Free T3 blood tests taken? If not ask for these to be done and if GP says (or lab wont) he cannot. Get these done privately if it is possible for you. We have recommended labs and members have been happy with their service.

  • Yes and all were in upper range

  • Do you have your latest results with the ranges you can post (on a new post) and you will get fresh responses.

  • Muscle fatigue is a symptom of hypo. Perhaps you are under-medicated.

  • Auntyp62,

    diogenes is an advisor for TUK and his wife has been taking Levothyroxine for 45 years.

  • Oooh, I shall look forward to his reply Clutter :) , they're always so wonderfully informative.

  • Hi Auntyp62

    I've just had a quick look at your past posts. Your thyroid journey at times sounds truely horrendous ! The lack of medical knowledge over the years is truely shocking.

    I've only been on levo for 30 years ( diagnised at 18 ) and am relatively at the start of my journey into improving my health. I do feel that as the years have progressed I've felt less benefit / more symptomatic on the same dose.

    How did you get on with your secondary Addison's tests ? I was on 150mg for 25 years, then some clever doctor reduced it to 125mg. And I've been a lot more symptomatic ever since. At the time and since I have been going through a lot of stress. So am quite concerned about the stress my adrenals have been under.

  • The test came back negative but it did spur me to go to an endincrinologist which my gp always said was not necessary. I do feel that when overmedicated (according to blood tests) my body adapted to dosage and I felt ok but each time dose is reduced to where it should be I have symptoms.........was just wondering if others were the same or do we lose effect after such a long time

  • I'm no expert but I wouldn't think it is something the body in effect gets use to and subsequently needs more of. I felt like my body was stronger and more able to cope in my 20's. Where as as my 30's & 40's have progressed I feel like my body has been less able to cope with not being optimal. Quite possibly due to increasing adrenal stress over many years. That's just my theory from reading other people's journeys and the way I've felt.

    Although there are so many factors that play a part that its difficult to tell whether adrenal fatigue is inevitable for anyone that has been over or under medicated for years.

    I hope you find some answers soon and subsequently feel better 👍

  • Maybe these links will interest you and Kitti1 . An excerpt from the first:-

    Dr. Lowe: First I suggest that you ask your doctor to question the scientific basis of the endocrinologists’ notion of "fine tuning" by TSH and thyroid hormone levels. If he does, he’ll learn that the changes he sees in your TSH and thyroid hormone levels are probably nothing more than natural variations in the levels. He would probably see the same variations if he always kept your thyroid hormone dose the same. I’ll briefly review some of the evidence that your doctor should read.

    TSH levels don’t significantly correlate day-to-day[1] or week-to-week.[2] One research group measured the TSH and free T3 and free T4 levels of ten normal young men.[3] When they measured the levels every 30 minutes for 24 hours, they found that the hormone levels were lower during the day and higher at night. During the day, the free T3 was 15% lower, the free T4 was 7% lower, and the TSH was 140% lower. When the researchers measured the hormone levels every five minutes for six to seven hours (7 PM-to-11 PM), the levels varied every thirty minutes. The TSH level varied 13%, the free T3 15%, and the free T4 11%.



  • Thank you shaws for copying me in. I'll read with interest, but slowly as I'm not great at the moment. 👍

  • I know exactly how that feels and you have my sympathy. It would be good if doctors would realise it but we cannot rely on them at all.

  • Hi auntyp62, yes, me too 1975 thyroid cancer. Most of that time I have been undermedicated and only recently have I introduced T3 and i am still waiting, hopefully, to find the right level of thyroxine that makes me feel well. Like SeasideSusie, I am self medicating on T3 because my doctor only uses T4 based on TSH results which drives me wild. So currently I am taking 125 mcg eltroxin and 20 mcg (10mcgxtwice a day) and that has still not lifted my brain fog. In a little while I will try 150mcg eltroxin plus the T3 and see what happens.

    Oh, I should add the for the first 2 decades or so, prior to the internet, I slept a lot because of fatigue, put on weight and lost lots of hair.

  • Update after hospital visit...apparently it's not the weakness in muscles causing my tiredness but the tiredness causing the weakness in muscles....back to endo and maybe a sleep clinic to find out why I sleep so much

  • It sounds as though you may be underdosed.

  • I do feel underdosed, my tsh 0.01free t4 was 24...free t3 5.6 and reverse t3 ratio 8.5

    For years I was overdosed...just wondered if my body got used to being overdosed and not happy in normal range.....

  • They should pay less attention to blood tests and more attention to the patients' clinical symptoms which they should endeavour to relieve but they don't know how to do so.

  • Been on holiday so couldn't reply. My wife has been on T4 (150 now 125) for nearly 50 years. Never had detectable TSH, and GP isn't worried. No signs of osteoporosis and only v occasional AF. Doesn't get muscle fatigue any more than a 78 year old might expect in normal health. I believe she is one of those subjects who JUST manage with T4 only but at the expense of suppressed TSH to get adequate T3. Until hips and knees surrendered, we were both keen hikers and fell walkers. No problem for her up to 10-12 miles - then the gas ran out. So we had to judge walking distance and difficulty first.

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