Thyroid UK
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How does NDT work ?

Hi there,

Hope this isn't a silly question (although I just tried to help my 9 year old with his homework and I was seriously I know my brain's not doing so well right now).

I have been titrating upwards to reach 2.25 grains of Naturethroid per day.

I know that T4 takes a few weeks to get working in your system and T3 is the quick surge of energy etc.

Should I either increase my dose (as symptoms continue to show themselves or worsen) or is it beter to wait to do a blood test in a few weeks as my T4 stablises?

Hope that makes sense



5 Replies

'T3 is the quick surge of energy'

Oh, that made me laugh! I'm on T3 only, and what I wouldn't give for a 'quick surge of energy! lol No, that's what doctors believe, but, honestly, have you found it to be true?

T4 does take six weeks to be metabolised completely, it true, it's a storage hormone that has to be converted into T3. T3 is only in the blood for about a day, during which time, it's sucked up by the cells (hopefully) and stays there fro about three days. There's really nothing quick or surging about it, in real terms, it's just comparing it to T4.

So, what is usually advised is increasing NDT by 1/4 grain every two weeks until you get to two grains, then hold for six weeks and retest. When did you have your last blood test? It depends on the results whether you continue to increase, or whether you start looking at other things for your symptoms. Have you had your nutrients tested? Vit D, vit B12, folate and ferritin? These all have to be optimal for NDT to work optimally. If you have nutritional deficiencies, you will still be having symptoms, no matter how much NDT you take. :)


Thanks Grey Goose.

Well, I noticed if I don't take my NDT at the usual time I struggle to function at all but it's been a while since I had a full round of bloods. I have been supplementing all that you've mentioned.

I seem to have become more hypo since my dose increase but I'll wait it out and see if things improve.

So - once T4 is metabolised then I should (theoretically) be in a good place and should know if I need to increase. Does that mean after 6 weeks I may need to decrease as well? Can you also find you are overmedicated after this 6 week waiting period or does overmedication show itself straight away with NDT?

Thanks so much,



There are no hard and fast answers to any of those questions, because we're all different. Some people might feel straight away that they're over-medicated, others not. That's why you need the tests.

Did you get tests before supplementing vit D, etc? If so, it would be a good idea to post the results on here, and tell us how much you're taking of each, to make sure you're taking the right amount according to the results. It's really not recommended to take vit D or iron without testing first. :)

1 like

IT is easy to miss your "sweet spot". After a couple of weeks you are thinking "I need a bit more" so you up the dose when what is in your body may be enough but not being fully utilised (does that make any sense? ).

I know I am near my optimum level but not quite. Blood tests showed I could go up a bit (despite my GP having a hissy fit). I have a built in indicator (tinitus) so just have to sit quietly and see how bad the ringing is!

I was really getting there but my brand of NDT cannot be found, so I have changed. All over the place at the moment. Such fun!

So it is sort of a combination of slowly, slowly with the dosage, helped along by blood tests and listening to your body. Hope you find your sweet spot soon.



Thanks that's what I wanted to know.

My tinnitus is raging and brain fog is really bad. This happened after I raised to 2 grains so, I actually added another 1/4 grain (thinking I was undermedicate) but it's not made an (immediate) difference. In fact, I feel more hypo than I did a while ago but I'm reluctant to keep on increasing and it would appear that's the right course. So, I have to wait a while to see what I'm like once everything is being used in my body?

I have ordered a blood test to check my vits, but will wait to test my thyroid.

Someone on here previously said that they couldn't raise their dose without getting more hypo symptoms. Instead they added a bit of T3 to their mix and felt good.

Were you on Naturethroid?

I hope you get yourself sorted soon. It's miserable when you think you've cracked it and have to re-start.

Good luck!


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