Thyroid UK
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Block and replace? How long is the average time to be on both carbimazole and levothyroxine?

Had to go to hospital today for a pre op assessment regarding a small op on my big toe.

After running through the usual medical questions, the nurse said that as I was on both of these drugs the anaesthetist might be unhappy putting me to sleep as the thyroid might go nuts and it could be potentially dangerous. Then I might have to have op after my own doc has taken me off the carbimazole (prob Sept).

The consultant thought it should be alright as they can do a different injection into the spine?

Obviously I am a bit concerned and I wont have the op unless its reasonably safe.

I just wanted to know what the average is to stay on block and replace? I have been on carbimazole since dec 2011 and on both since april 2012 when I went underactive.

Any comments appreciated :)

3 Replies

Hi I think the average time for carbimazole is 12 - 18 months up to 2 years. I am not sure if this is the case for block and replace but would have thought so.

Just for your info the spinal block is still a good way to have an op and in some ways may be better than a general anaesthetic.

Do ask to see your endo and find out how long they expect you to be on your meds and what your latest blood results signify. Good luck.


I would seriously consider the local anaesthetic, it is often much easier to cope with than the general and you will not feel any pain.

My son took 2 months to recover from the general anaesthetic, with dizziness/nausea on standing for the whole of this time, he was the next year diagnosed as hypothyroid, I know you are 'hyper' but perhaps all of us are more 'delicate' when it comes to general anaesthesia?


i m hyper since feb 2012 on carbimazol now ptu

saw my endo last week and asked how long i could be on meds for and he said 10 20 years!

think it depends on your endo

i m not on block and replace though so that may be different

my daughter had 2 ingrowing toe nail ops a few years ago and had a local anaesthetic each time

she was fine

good luck with op



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