Does T4 level matter when on NDT?: I recently had... - Thyroid UK

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Does T4 level matter when on NDT?

I recently had a blood test done at my health centre to placate my GP, he is concerned about my suppressed TSH. I just ignore him when he says anything, I have tried explaining that TSH levels are irrelevant when medicating but it does not sink in, though he does accept that I am aware of the risks and will monitor me while I self-medicate. Anyhow my results from 8:50 am, 12 hours after taking my 2 grains of NDT, came back as follows:

TSH 0.05 (0.34-5.6)

T4 7.3 (7.9-20.0)

T3 6.0 (4.0-6.6)

My T4 levels have always been low on NDT but this is the first time they are below range, my T3 levels are constantly ¾ of the way up the range. I understand when taking T3 only this can happen but I take NDT which contains T4 as well as all the other Ts. I have tried increasing to 2.25 grains earlier in the year and felt a little better but then I started supplementing with Bs, B12, C, zinc, selenium and magnesium, plus ferrous fumarate for 3 months, and felt like I might have overcooked it slightly so dropped back to 2 grains.

Should I try to increase my T4 levels or do they really not matter?

6 Replies

The blood tests for thyroid hormones, as far as I know, are for the use of T4 only. Therefore, when on other thyroid hormone replacements they may not be equal to being on T4 only.

T4 is the inactive hormone - it's job is to convert to T3 and your T3 is good so I wouldn't worry. :) The most important question is 'how do you feel'.

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Does anyone know what is it like to really feel normal/healthy. A good day is one where I can wake up feeling like I have slept soundly and not resent having to live through another day.

My mental health has never been good and I have had to go back to my old job for the last few months. Apparently it is has not been possible to employ anyone who can actually do the job as well as I did so I have been called in to correct all the mistakes and retrain the third person to do the job since I left 20 months ago. I am a little exhausted, stressed and not sleeping well but hopefully that will pass now that I am no longer needed, at least until the end of the tax year.

The only upsetting thing is that my son seems to have inherited my mental attitude and is currently battling his own existential crisis so I also worry for his future.

The good news is I have lost nearly a stone after having to follow a low carb high fat diet to help control my husbands blood sugar levels, he has type 2 diabetes but has only lost 1/2 a stone though his blood sugars are a lot better.

Life goes on no matter what.

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The good news of your weight loss is excellent, especially just before Christmas when you can indulge a little without guilt :)

In answer to your first question, for me the answer is 'yes' I feel well and healthy and am on T3 only. Levothyroxine wasn't for me. NDT I tried several and it was superior to levo but it was T3 only that worked for me. Others find NDT does the same. So, I've not had a gene test which proves someone cannot convert T4 (levothyroxine) so assume I have.

I like the way they used to prescribe, i.e. diagnosed upon symptoms alone and gave NDT until symptoms were relieved. :)

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FT4 level isn't important because FT3 is good. It's not uncommon to see FT4 below range when patient is taking NDT.

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I have been on NDT for 2 years, initially felt much better, however my t4 remained below range on it and I was having some symptoms, fatigue and lightheaded. My endo put me on 25mg levo alongside the NDT which was reduced a little and this suits me. My t4 is still low in range but not under now and my symptoms have gone and Ive been on this combination over a year now. We are all different as to what we need but thought I would share my situation.


In the book "Tired Tyroid" it is explicitely mentioned that fT4 has a function, she describes that she gets brainfog if her fT4 is too low. Everyone is different but I could imagine that a lot of people need extra ft4 to their NTD. I am experimenting with the same at the moment, but too early to tell.

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