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Thyroid UK
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Would like to try T3 only- dosing advice please?

Hi, i'm currently on 3 grains of NDT and 1 x 25mcg T3 daily. I would like to try T3 only. I was doing wonderfully on NDT for 4 long lovely months but sadly since the New Year my hypo symptoms have returned. Have tried increasing NDT/T3 in different ratios but it just doesn't seem to have any improvement but it does send my heart rate above 100bpm, so i drop back down.

Would like to switch to T3 but am unsure how to dose and my brain won't function despite reading several posts about it. Please help!

6 Replies

Your combined dose of NDT and T3 was quite high - equal to around 400mcg of levothyroxine.

Maybe that's the reason you weren't feeling so good.

The usual way to introduce NDT is to start off on 1/2 gr (Unless you were already on levo and then you just take the equivalent of NDT) you then increase by 1/4 to 1/2 gr every 2 weeks till you feel well.

When you said you were fine on NDT was that before you added T3? 

Have you had a recent blood test as that would allow members to give their responses. If you've not had one for a while I would advise a new one so that you can start afresh with your hormones i.e. TSH, T4, T3 Free T4 and Free T3. Also vitamins/minerals if you've not had them for a while.

Are you aware of the best procedure to take in having blood tests?



Have you had FT4 and FT3 tested on that dose?  It's quite high and overmedication can make you feel awful.

1 grain NDT is equivalent to 25mcg T3.


To be completely frank i'm all over the place. I feel like I'm losing the plot. I had tried t3/t4 combo's for hashi's for the last 3 years since diagnosis (self medicating). Usually the case was i found a level i felt great on but a few months later the hypo symptoms were back, so I increased and the symptoms abated once again. Then i tried NDT for the first time last year and felt amazing. Hair and nails grew lovely. Could lose a lb or 2 a week with a healthy diet (a first!), felt well, looked well. Skin was great, body temps great. Etc etc. Really thought i'd found 'the one'.

But Straight after christmas last year everything went to pot. So i tried NDT and t3, a different type of NDT, i even went back to levo and t3 which I didn't think i'd ever do. But the symptoms (cold, tired, brain fog, weight gain, constipation, poor urine output, fluid retention) etc continues. Yet...my bpm is 80+ and i feel hyper sometimes. So thought perhaps i have high rt3?

Haven't had a blood test for about 6 months. To be honest I darent as my TSH i fear will be hyper.

Just don't know what to do any more 

Thank you both for taking the time to reply



TSH is likely to be suppressed on the doses you are taking.  It's not important as long as FT3 remains within range.  Ideally you'll have a blood test after every change of medication and dose adjustment to check FT3 remains within range and you are optimally medicated. 

It may be a good idea to have ferritin, vitamin D, B12 and folate which are commonly low/deficient in hypothyroid patients  tested too.

You can order private tests if you are reluctant to ask your GP to test.  GP is unlikely to do FT3 anyway.



I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


Thank you, we are away on holiday from today but when i get back I'm thinking of ordering the blue horizon test that also does the rt3. 

I didn't know that about it being ok for TSH to be supressed so long as ft3 is still in range. 

Thanks again for your help



Have a good holiday!


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