Thyroid UK
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Has levothyroxine stopped working?

Hi there, I was diagnosed with hashimotos 2 years ago and hypothyroid in december, i started on 25 mcg levothyroxine in january and after some initial teething problems which I wrote on here about, Ive been really fine.. until very recently. I did have some blood tests done last month which said that I was normalised again. However the last week Ive gone right downhill where my sleep has gradually got worse like it was when I was diagnosed hypo. I knew something was wrong when I woke up at 5am today with less than 5 hours sleep, felt terrible all day, when went to bed tonight just nothing cant sleep at all. Hence here writing to you guys. Im also suffering with a lot of pain, I have fibromyalgia, and this has also flared up. Basically I feel terrible and like Im about to crack up. Oh, and when I went to bed my heart was racing I timed the beats and it was 98 lying down and it just went on and on, think it has calmed now. Is it worth going to see my doctor yet or should I wait. I have to go to work I just started fulltime and I so dont need this!

3 Replies

Hi I may be wrong but i think the GP may just be testing TSH, on its own it is useless. You always need TSH, T4 and Free T3 tested.You are on a very low dose of Levo, usually it is retested 6 weeks after starting, adjusted if needed ( often is ) then 3 monthly all 3 tests until you feel better. tests must be the3 tests but even then id all depends on how you feel.Also you may have stopped converting all the T4 to FT3 that you need, this is common and can happy any time. Then you need T4 ( levo) and T3 on a script. Only the blood test will show this. T3 on a script dos slightly lower the TSH, helps symptoms especially weight. 20mcg to start with . It must be split into 2 doses 12 hours apart ,as it gives a high , If you have a prescription take half the dose for the first week , as some times it causes problems at the beginning.If the GP will not test properly you can pay for the tests yourself.

Best wishes,


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Are you still on 25mcg levothyroxine?


Hi Shan, I don't think levo stops working exactly, maybe technicially if it turns into reverse T3. But chances are you need an increase of your meds. Are you on a very high dose right now?

I find when my blood pressure drops, my heart beats faster, I assume that is to maintain blood pressure. I'm pretty sure it's because the thyroid is low at those times. It's such a guessing game.


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