Thyroid UK
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High T3 Low T4- help !

Hello guys - so advice greatly appreciated ! I'm not sure where to go with my dosing ! Around 6 months ago I began to self medicate. My T4 was under the range, I couldn't function but because my TSH was completely normal 1.5 ish my Dr refused to prescribe anything. My brain and body had packed in. I am now on 3 grains of NDT/ 2 adrenal supplements and feeling much better. My latest blood test showed a T4 within range but nearer the bottom (10.2 range starting at 9 )and T3 too high by a couple of points !

The endo dept who took this test has written a letter to the dr saying that I must stop all self prescribed medicine immediately or I risk the chance of stroke or even death (seriously). I did not stop taking NDT prior to the blood test which I now realise I should which might have made the T3 inflated however this does not solve the puzzle of the low T4 ? TSH is now 0 btw. Advice much appreciated x

6 Replies

Whenever T3 is in the 'mix' of thyroid hormone replacements, the T4 is lower due to T3. What your Endo and Doctor are using is the blood tests which were introduced along with levothyroxine alone, so with T3 in your dose tests wont be compatible.

The Endo is making an error and it is due to you taking your dose before the blood test. That definitely skews results, even if you were on levo alone.

Ask your GP to do another blood test and this time take all the precautions required by you:


1. The earliest possible appointment and don't eat before it although you can drink water.

2. Allow 24 hours between your last dose of NDT and the test. The day before put your tablets elsewhere so you aren't on automatic pilot on the day of the test and take them.

You won't get a heart attack or osteoporosis but might do, even if on levo, if dose isn't correct for you. :)

(I am not medically qualified).


Thanks Shaws. And will this be a true reflection of whether I actually need more medication rather than less. I have read that T4 should be in the top half of the range which is going to take a lot of medication if I take 3 now and it's still near the bottom ! Or does it not matter so much if T3 is ok ? Best Adrienne


The true reflection if thyroid hormones are doing their job is by how the patient 'feels'. If well they're on the right dose - if unwell need increase.

You state above :-

I have read that T4 should be in the top half of the range

I am sure that would apply only if you are taking levothyroxine alone but not on NDT.

I am on T3 only so don't take T4, therefore if my bloods were taken the T4 will be no-where I assume. The best thing is I am well with no symptoms which should apply to everyone on a proper dose of hormones which suits them. I had to try several NDTs before I found the 'perfect' one for me but as stated I take T3 only now.

This is a link which you might find helpful:-

1 like

Thanks x



If you were taking Levothyroxine only you would need FT4 in the upper range to deliver reasonable FT3. As you are taking NDT which has T3 it's not important to have high FT4. Ideally FT3 will be in the upper third of range.


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 ! X


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