Thyroid UK
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Bloods on NDT - Low T4

What do your blood test results look like on NDT? Could those on NDT respond please? Or those that know the answer? :-)

I have swapped some of my T3 to Thiroyd 7 months ago, and my T4 levels have increased but they are still very low, not even in the ref. range... I would have expected that my T4 levels would be mid-ref. range. (I'm taking 25mcg T3 at 3am, 1.5 grains of NDT sublingually at 11am and 1grain NDT at 5pm).

My bloods in March 2016:

TSH: 0.01 (0.55-4.78), FT4: 0.08 (0.89-1.76), FT3: 3.39 (2.30-4.20)

My bloods in Nov 2016:

TSH: <0.01 (0.55-4.78), FT4: 0.63 (0.89-1.76), FT3: 4.48 (2.30-4.20)

My TSH seems even more suppressed (is the low TSH going to have any health consequences?? Like bone density issues??)

I didn't take any thyroid meds for over 12 hrs before the bloods were taken.

In the Nov blood test I also had Magnesium tested (0.86 Ref. range: 0.77-1.03) and I've been massively pumping Mg in the last 3 months (Epsom salt baths and transdermal Zechstein Mg) so I expected my Mg levels to be higher. How can I raise them? Do I just carry on with what I'm doing?

Also my white blood cells are a bit out of whack. My Neutrofil was below ref. range but my lymphocyte was above the ref. range! This worries me. What does this mean?

My triglycerides level was also below ref. range (in both blood tests in March & Nov) and so was my total cholesterol in Nov (even though my LDL and HDL cholesterol are well within ref. range).

I'm worried that with these levels my doctor will not prescribe T3 anymore :-(

I was tested for Hashi's 1.5 years or so ago but it was negative. They tested both markers.

I'm in Hungary.

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My Free T4 is at the bottom of the range, and free T3 at the top, with TSH at zero. Its been like that pretty well all the time I have been tested on NDT(I wasn't test for the first few years!). You should expect TSH to very low as soon as you start taking anything with T3 in it.

So effectively, as soon as you start to take T3 or NDT your own production of Ts will stop. And if you take them for any length of time TSH is permanently suppressed.

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There's no point in testing magnesium. The result will always be in range. But, that won't mean anything, because of the way the body handles magnesium. I would just keep taking it, if I were you.

Don't leave too long between your last dose and the test - maximum 12 hours - or you will get a falsely low FT3. But, it won't make any difference to your TSH.

NDT is not meant to be taken sublingually - no thyroid hormone replacement is. The molecules are too large to pass through into the blood stream. It will just dissolve into your saliva, and you will swallow most of it - some of it will probably hang around in your mouth until it binds with the next food you eat. But, you won't be able to control the amount you absorb, the way you can when you just swallow it. It's a very haphazard way of taking it, no matter what they say on STTM.

My TSH has been suppressed for years. I take T3 only, so my FT4 is zero. I don't see it as a problem. :)


Oh, I read that it's better to take NDT sublingually because it gets absorbed better. That's why I switched to taking it sublingually. How far away from food am I suppowed to take NDT? I know that you can take T3 even with food and when I was on Levo, I had to take it first thing, on an empty stomach...

I took the last dose on NDT about 13-ish hrs before the blood was drawn, but my FT3 levels were still out of range too high. What does this mean? Am I on too much T3? How am I supposed to know if I'm taking the right amount of meds ATM, if the blood tests are meaningless?

Thanks! Xx


No, you can't take T3 with food. You can't take any thyroid hormone with food. It will bind with certain nutrients and become unavailable for use by your body. You should take them all - levo, T3, NDT - on an empty stomach, swallowing with a glass of water, one hour before food or any drink except water, and two hours before other supplements or medication.

Who said the blood tests were meaningless? I just said not to leave too long between the last dose and the test or you would get a falsely low FT3. I didn't say that's what you had. And I said that because you said that you'd left 'over 12 hours', which could mean anything. I didn't know you meant 'about 13' hours. Do you always leave about 13 hours? The aim of the exercise is to always do things the same way so that you can compare results. And, it would help if you were more precise.

But, as you say, your FT3 is slightly over-range. If it were my FT3, that wouldn't bother me, but, it might bother your endo - if he even looks at the FT3! He's more likely to be more concerned about the low TSH. Which isn't a problem, either, but he doesn't know that. You might have a bit of a fight on your hands. Try and compromise, but saying that you'll lower the T3 a little, rather than giving it up completely.

Does your endo know you're taking NDT? If so, suggest you decrease by half a grain, rather than touching the T3. But, that won't bring your TSH up, because you are taking T3. The TSH is supressed because you don't need it anymore when you're taking T3.

But, how do you feel? Do you feel over-medicated? Do you still have hypo symptoms?



I take the T3 at 3am so that's definitely away from food :-)

I'll have to make sure I do leave 1 hr away from food with the NDT then and I'll just swallow it.

I have never done a blood test on NDT before as I gave been only taking it for 7 months. I took my 5pm NDT a bit late the day before the blood test and then I didn't take my circadian dose of T3, and had the blood test at 7am. I don't know if this is a good way to go before the blood test? Please could you advise?

I don't see an ending, this is a GP that prescribes my T3. I think I to,d her that I take NDT too but she thinks T3 is my main med (so I can get more prescribed and squirrel it away for when we go back to the UK next year as I'm worried about having issues getting it prescribed again, although my GP back in the UK used to prescribe it for me but I heard that things have changed in the last couple of years...)

I'm not that bothered about blood test results just worried that the doctor might be as she doesn't understand the effect of the NDT and T3 on blood test results and she already said that suppressed TSH can cause osteoporosis?

I'm a bit muzzy-headed and dizzy at times but when I regularly sleep for 8 hrs / night, this disappears. My only other symptom is the back and muscle ache I had for nearly 2.5 years now, but recently I found out that this is because my hip went out of alignment (I gave birth 32 months ago) and my misaligned hip is pulling on my back and leg muscles. It was put back twice and I feel asymptomatic afterwards, but then my hip goes out again... Very frustrating as I'm so careful. I have to build up more muscle and strengthen myself. I'm still breastfeeding so that could cause more relaxed muscles too, although my baby is losing interest in breastfeeding now, so when she weans herself, I'll see if that helps with muscle stability...

I do get quite tired if I don't sleep 8 hrs / night.

I don't seem to have hyper symptoms although I do get hot very quickly (but I also get cold fairly quickly...). My temperature tolerance is not the widest if that makes sense. Thanks!


Yes, it makes sense. Your thermostat is broken! lol Same as mine. I think, if you're hypo, you're hot all the time.

Yes, it is a worry, doctors being so ignorant. They don't understand blood tests at all. And yet they use them to control our lives! It's all wrong. That's why I self-treat.

So, it was more like 14 hours you left between the last dose and the blood draw. Under the circumstances, that's ok, but just make sure you do the same next blood test, so that you can compare them. But, be aware, your FT3 could have been higher had you left just 12 hours.

As I remember it, it's very difficult to know how you feel when you're breast feeding a young baby. You'll be able to take stock a lot better when she's weaned, as you said. But, you don't feel hyper, so that's good. I just don't know what you can do about your doctor, that's all. Because you do appear, on paper, to be over-medicated. :)

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