Too much Thyroxine

Hello ,

I was wondering if anyone would be able to help me . I have been suffering from anxiety and panic for over 2 years. I have been on thyroxine for about 8 years . At the one time 100mg . For the last year 50mg taken at night . I have not been feeling well for years. I had a blood test done and the results were showing a TSH level of 0.02 . This would indicate over medication. I have now reduced to 25mg . Should I stop taking the medication till it regulates or should I continue with the lower dose. How long will it take to alleviate the symptoms as I have all the symptoms of an overactive thyroid now.

Has this happened to anyone else ?

Thank you .

Tracey .

41 Replies

  • TSH level of 0.02 does not necessarily mean you were over medicated. You needed your Ft4 and in an ideal world Ft3 test results to know that. You could maybe get those tested again and post results with ranges on here and find out what is going on now :)

  • Hello thanks for replying. My T3 level was 4.1 and free thyroxine was 21.8 .

  • What are the reference ranges ? Well ft4 is probably on high end , but if ft3 is for example 3.5-6.5 then 4.1 isn't good enough.

    You could be also converting ft4 to rt3 so in that case lowering T4 and adding T3 would makes a difference and you'd feel much better.

    So regardless your low TSH which could trigger the question of being over medicated , you can be very hypo on cellular level.

  • Thank you Justina . Would you advise me to take T3 ? Is that what you are saying ? I am sorry but all these different readings are confusing to me . I have been so unwell for so long now . I am unsure what to do for the best. Decrease , stop or go to see an endocrinologist.

  • I can't say if taking T3 is necessary as like you have been advised by other members , reducing T4 can do the trick and you will better with a bit less T4.

    But if reducing T4 would also reduce conversion to T3 , then adding T3 is the way to fix it.

  • Oh no no, please don't reduce your dose again. You're almost certainly undermedicated. TSH - once hypothyroidism has been diagnosed - presents a very inaccurate picture of whether you're on enough medication. I'd eat my hat (if I had one!) if you were on too much. In fact, I think it's far more likely you need 100mcg again.

    Does your doctor ever test FT4 and FT3? If not, ask him/her to.

  • Thank you for taking the time to reply my doctor tested both thE FT4 and F3 I posted the results above , she has advised me to reduce my medication if I have anxiety , palpitations and weight loss. I have not had weight loss but have no appetite and other symptoms of Hyopthyroism . It was under active .

  • It is very common to have ambiguous symptoms, but for whatever reason docs think anxiety, sleeplessness and palps are without doubt symptoms of overmedication. For me (and others here) they are all hypO symptoms. I had the worst anxiety ever before diagnosis and when undermedicated.

    I agree that you seem to be converting poorly and low t3 can make you feel miserable. You may need a little t3 and/or your nutrients may need a boost. Do you know if your ferritin, iron, folate, vit d, b12 are optimal? Most of us struggle to keep them in range.

  • Thanks for your response. I have not had those tested. So I don't know . I had my cholesterol tested and it was 7. The doctor suggested statins though I am gong to try to reduce it without them first .

  • That is more evidence supporting the theory that you're undermedicated. High cholesterol is a hypo symptom. It's not a bad idea to put off treatment as it may level out after you're on enough meds.

  • Welcome to the forum, TJc64.

    TSH testing is sufficient to tell whether you are under medicated because TSH will be high but having suppressed TSH 0.02 doesn't mean you are over medicated. If you feel over medicated then you can see whether the reduced dose makes you feel more comfortable. It will take 7-8 days for the higher dose to wash out and you can speed that up by skipping Levothyroxine for 2-3 days.

    Please bear in mind that anxiety and panic can be due to under medication as well as over medication. It would be better to order a thyroid test with TSH, FT4 and FT3 before changing your dose. You can order private thyroid tests via

  • Thank you for your help . My doctor has told me to reduce medication .

  • TJc64,

    Yes, GPs often think low TSH means the patient is over medicated, but unless your FT4 and FT3 are over range you are NOT over medicated.

  • I have posted the results above . I would be grateful for your thoughts . Thank you

  • Clutter's advice is good. Try the reduced dose for a few weeks and see how you feel. If you are worse (after at least two weeks) resume your previous dose.

  • The T3 and T4 were within normal range .

  • TJc64,

    In that case you are NOT biochemically over medicated even though TSH is suppressed. I suspect you may feel under medicated on 25mcg in a couple of weeks and if so you will need to reinstate 50mcg.

  • Thank you for the advice . Much appreciated. Would you advise me to see my endocrinologist again . I have not seen him in over a year ?

  • TJc64,

    Only if you found him helpful previously. Too many endocrinologists want to dose via TSH result without taking into consideration FT4, FT3 and symptoms for my liking.

  • I did not find him particularly helpful . I notice on your site that a lot of people supplement with T3 as well as Thyroxine. Also that you have advised to have a test done by post . Testing for B12 and Vit D . My Vit D levels were low so I have supplemented that for a year . Would you advise me to get re tested via your website ? Also that the brand of medication can make a difference ?

    Sorry for all the questions.

  • You don't look as if you are converting very well, because your FT4 is quite high, and the FT3 low. So, adding in some T3 would probably help you a lot. You need that FT3 higher. :)

  • fT3 will always be a bit low if fT4 is near the upper limit of the reference interval, so you can't infer deiodinase efficiency in these cases. This is because the high fT4 and low TSH reduces thyroidal output (if there is any) and also reduces type-2 deiodinase (T4 -> T3 conversion). If fT4 goes even higher then type-1 deiodinase (T4 -> T3 and T4 -> rT3) takes over giving an impression of good conversion. I think you can only get a rough indication of conversion efficiency when fT4 is at or just above mid-interval.

  • Thanks for your response . Though to be honest it's all Double Dutch to me. 🤔 I just want to feel better .

  • That's OK, it's academic. Just see how you do on the reduced dose and see which dose you feel better on.

  • Yes, well, for all intents and purposes, it adds up to the same thing - reduce T4 and add in some T3. No-one has the understanding or the interest to go into the details like that, so it really doesn't help, does it.

  • Sorry about the complexity, it would be much easier if it were as simple as most endocrinologists claim. The point is you can’t infer poor T4 to T3 conversion from these numbers. In Tracy’s case, she is experiencing hyperthyroid symptoms and so the logical approach is to reduce her medication and see how she does. Adding in L-T3, which is more potent and shorter acting, would make her situation worse (assuming she is hyperthyroid).

    If a reduced dose makes her worse substituting a little L-T3 (liothyronine) for some L-T4 (levothyroxine) would be an option.

  • The complexity doesn't bother me. It's just that no doctor is going to go into all that to find the root of the problem, so it's not really worth mentioning.

    She's on T4 only, her FT3 is low. Her anxiety is more likely to be a symptom of under-medication. If you reduce the T4, her T3 is going to reduce, too. And, whereas the lower level of T4 might help, there's no guarantee it's going to improve her conversion. But, a lower FT3 level might exacerbate her symptoms.

    Of course, if she wants to try it, why not, but personally, I would go for the T3 - not suggesting she takes a cart-load, just 10 mcg, perhaps. It's not as potent as you might think.

  • It's not a case of less L-T4 meaning less fT3. The body regulates thyroid hormone levels so as to achieve euthyroidism. If the hormone levels are too low it tries to stimulate more hormone via TSH and enhance D2: T4 to T3 conversion. If hormone levels are too high it lowers TSH to reduce thyroid output and increases D2 which produces rT3 as well as T3. Tracey's fT4 is 21.8 so there is room to reduce her levothyroxine. This will raise TSH which will promote D2: T4 to T3 conversion and stimulate her thyroid to produce more homone.

    It may be that her symptoms are not due to hyperthyroidism in which case they may be hypothyroid or not related to thyroid. However, hyperthroidism is a distinct possibility and it makes sense to see what happens on a reduced dose. Giving L-T3 to a hyperthyroid patient is worse than giving L-T4.

    Tracey, you say you have all the symptoms of hyperthyroidism, can you give us a list, this would be helpful.

  • Yes, I know all the theory. But that is based on healthy people. And, as I'm always saying it's not helpful to compare healthy people with hypos and expect them to react the same.

    Yes, Tracey, it's always helpful if people give full details. :)

  • If hormone levels are too high it lowers TSH to reduce thyroid output and increases D2 which produces rT3 as well as T3.

    Sorry, this should read 'D1' not 'D2'.

  • I understood what you meant. :)

  • Hello Jim111,

    I'm really interested in what you have to say. Would you perhaps consider writing a post re - understanding conversion rates etc.?

    You seem to have a scientific approach. Maybe this is your field?

    Could you also expand on Dr. Anthony Tofts thought of raising Ft4 levels over range in order to raise FT3 high enough in range especially in those of us like myself who have secondary hypothyroidism.

    Presumably for secondary hypo the TSH doesn't play much of a role with the D1 or D2 thing because the TSH doesn't work properly.

    Crikey this is complicated. On size does not fit all!!😜

    I need to raise my dosage again again but my endocrinologist is considering which one to do - levo or T3 meds. I am still exhausted.

    My current results are

    TSH 0.1 (0.4 - 4.6)

    FT4. 15.6. (12-22 )

    FT3. 5.4. (3.1-6.8)

    I'm not trying to gate crash someone else's post I just feel that this is relevant to what is being discussed.

  • Hello , what is secondary Hypo ? Thanks

  • Primary hypo is where the fault lies within the thyroid gland.

    Secondary is where the fault lies within the pituitary gland and doesn't produce enough TSH

    Tertiary is where the fault lies within the hypothalamus gland and doesn't produce enough TRH.

    All treated identically with thyroid replacement.

  • What if you're secondary hypo and don't have a reliable TSH? I know this is complex and loathe asking but if you've got any knowledge of this Jim could you share it because trying to get levelled off when you're secondary is a Nightmare!

  • I get anxiety and panic when I am under dosed. Apparently if our bodies are short of thyroid hormones then adrenaline is released to compensate for it and it is the adrenaline that then causes the anxiety and panic.

    My Doctor reduced my dose according to my TSH and the anxiety symptoms as she thought I was over medicated and I explained the adrenaline connection to her and she looked at me blankly.

    She then wrote to an endo. for advice and when I went back to see her, she admitted I was right about my explanation and agreed to increase my dose again.

  • Glad the endocrinologist concurred.

    My adrenaline goes through the roof when my thyroxine levels are too low. Especially after exercise or over exertion.

    Makes me a panicky, anxious, nervous wreck. Terrible.

  • Me too. Shaky/jumpy for no reason. When undermedicated I feel like I spend my days cowering like a mistreated dog. (I edited this because I don't routinely spend my days this way. :-) Only when very hypo.)

  • Is this a thyroid problem or an anxiety disorder? Which I believed myself to have these last 3 years . My TSH levels have been constantly high . Despite reducing the T4 by half .

  • Well I guess that depends. If it responds to thyroid hormone I'd say it's a thyroid problem. :-)

    If you're reducing your t4 you're increasing your tsh. If you want to lower tsh you need to increase levo.

  • At low levels the TSH can be irrelevent. It is all doctors dose on and it is WRONG.

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