Thyroid UK
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Treatment of hyperthyroidism

I was diagnosed with hyperthyroidism some months ago.

My T4 was at 45, and my TSH had given up with a reading of <.01

I was put on carbimazole, initially 40mg/day. This got my T4 down to 11. I was told to reduce the carb to 20mg/day

But, my latest blood tests shows that my TSH is now approaching 10, whilst my my T4 remains at 11.

I was told to further reduce my carb to 10mg/day.

Is the TSH fighting with the carbimazole?

7 Replies

I am sorry you've not yet had a response. I have hypothyroidism but a member who is hyperthyroid will reply when they read your post.


Thank you


Do you know what the reference range is for the t4? It could be low or high depending on the lab. Reference ranges vary a lot from lab to lab.

I suspect your t4 is actually at the low end of the scale, hence your high TSH. If your tsh is approaching 10 it means your thyroid isn't producing enough t4 and t3 and that is likely why your doctor wants to reduce the carbimazole further.

Ideally you want your TSH below 3 and your t4 in the upper part of the range. It sounds like the carbimazole is still suppressing your t4 production too much and this is why your TSH is rising. A further decrease should hopefully allow you t4 level to rise which should then cause your TSH to drop. If this doesn't work, your doctor may stop the carb altogether. If that doesn't help then you may need thyroid hormone replacement. Hopefully the reduction in carbimazole does the trick. There can sometimes be a slightly delayed response to a reduction.

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Nov-14<.01 36.2

Dec-14<.01 45

Those are my readings since 2006, something went wrong in Nov2014. I did not take any form of medication before this date.


ok. From your previous results your current t4 look to be on the low side. Your doctor is wise to reduce your carbimazole and may need to stop it altogether. Too much carbimazole means that your thyroid doesn't produce enough thyroid hormone and this means that your TSH rises to try and get it to produce more. This should come down when the carbimazole is lowered enough to raise your t4 level.

I hope you and your doctor manage to get it under control soon. It must be very frustrating to feel poorly and not know when things are going to get better.


I am now at 10mg/day carb. I am interested in my next blood test result.

Thanks for the input.

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My latest results taken on 20/05/2015 were

T4 14.6

TSH 1.1

My GP has further reduced the carb dosage to 5mg/day.

It seems that I am losing hair since I was at the lower range of 'normal.

Will this stop now?


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