Thyroid UK
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Effects from reducing NDT

Good morning

I am still trying to get the right dose of NDT and my FT3 & FT4 are at top end of range so nearly over medicated and I have been given advice to supplement my vitamins as those results are low. So, in my wisdom I thought I would reduce my NDT from 4 grains to 3 grains and after a couple of days did not feel so good so increased up to 3.5 (which I take at 12-2am and when still not great I took another .5 at 3pm. (I usually took the 4 grains at 1 pm).

So I have been told that because my vitamins are deficient I need to get them up as the NDT will not be utilised - hence the thought that I might as well reduce th NDT.

So question finally - when reducing NDT should you do it gradually 1/4 grain at a time over 3 weeks like you would the increases.

On 4 grains I did not feel at all over medicated- I was expecting it to be simple and feel anxious, heart racing, signs that you were definitely over medicated but nothing in this journey is simple!

5 Replies


If your thyroid levels were within range you were not biochemically over medicated and there was no reason to reduce dose unless you felt over medicated.

I'm afraid there is a lot of nonsense spoken about thyroid replacement not being utilised unless vitamin and mineral levels are perfect. Vitamin deficiency can make you feel very poorly but it does not stop NDT working. I was severely vitD deficient, folate deficient and had low B12 but Levothyroxine was working because my TSH was low with FT4 and FT3 good at high doses and as I have no thyroid gland it must have been the Levothyroxine working for this to happen.

ps when you are close to being optimally medicated on NDT 1/4 grain dose adjustments are a good idea as small adjustments will help you avoid over and under shooting.

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Thanks, I am getting mixed messages about the vitamins but it kind of makes sense as being on 4 grains would put me over on the blood test but it hasn't sent me over active which is what I was expecting to do.

I think I will return to 4 grains and when I get results in June which will almost certainly send me over I will slowly reduce by 1/4 grain.

Is the Thyroid Patient Advocacy forum linked with you as I seem to be getting different messages about the vitamins and other stuff from each site, I thought you were connected with each other.



Thyroid UK and TPA are separate charities and separate fora.

Deficient vitamins will certainly make you feel unwell and anecdotally people may relate that replacement works better for them when ferritin is 70 or vitD 100 but I don't think that is the same as saying it won't work when levels are lower.

Ideally you will take the least amount of NDT on which you feel well and ensure FT3 remains within range. If you think 4 grains will over medicate you it would be better to remain on 3.75 grains.


This doctor had the right idea when treating his patients. Nearly all doctors followed this route before the blood tests and levothyroxine were introduced.

1 like

Well. This is interesting stuff, Clutter. I think you must be right - after all, Kazza's bloods seem to bear out what you are saying. First time I've heard it said here, though. You might have just posted a game-changer :-)


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