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Thyroid UK
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Is Natural dessicated thyroid weaker than levo

I know that seems like a daft question but what I cannot get my head round is the following.

I was on 50 mcg of levo and my results were higher than me being on 2 grains of Erfa. My levels have actually fallen since I have been on Erfa. There is probably a simple answer to this but my poor befuddled hypo brain is not playing ball.

Thanks L

11 Replies

What do you mean by your 'levels'? Do you have any actual figures with ranges? Sorry to answer a question with a question, but it is impossible to respond without a little more information. Remember, too, that NDT is completely different from Levo. Levo is a synthetic form of T4 only, whereas NDT has T4, T3, plus T2 and T1.

There is a chart at the bottom of this page to help you: thyroiduk.org.uk/tuk/treatm...

But please do put your results on here.

Marie XX


Hi Marie

No problem, levels were as follows

on 50 mcg levo

TSH 5.49 (0.35-5) T4 11 (7-20) T3 5.5 (3.5-5)

on 1.5 grains Erfa

TSH 2.21 (0.27-4.2) T4 12 (12-22) T3 4.8 (3.1-6.8)

The second row of results were done after taking my meds (private doc had instructed me to take them so result will presumably show higher t3 than it acutally is)

I am now on 2 grains erfa. It just seems to me that my T4 and T3 have dropped or am i going barmy.


When you are on thyroid hormone replacement, the most important question to be asked is 'how do I feel'. If unwell you need more meds and if you feel over-stimulated you reduce the dose slightly.

T4 is a prohormone (it is not active) - it is supposed to convert to enough T3.

NDT contains all of the thyroid hormones which we would naturally produce, i.e. T4, T3, T2, T1 and calcitonin, so you cannot compare like with like. As Marram says, one is synthetic and one natural either from pigs or cows so the likelihood of identical blood tests results is unlikely.


Hi shaws

I feel dreadful. Very fatigued, awful leg pains, dizzy - far from feeling like 'me'.

I know that you are supposed to raise the dose of NDT until symptoms are resolved. It just worries me taking more and more meds. Maybe this is something I need to get my head around.

I have in the back of my mind that the endo said i would only need 25/50 mcg levo.She was quite happy to leave me on that dose with a TSH of just over 5 whilst on levo. Her reasoning being that i had a high reading of T3. She said it was not important that my T4 was low as long as T3 was high. I decided to try NDT at this point and have been struggling since.

I had expected to see some light at the end of the tunnel whilst taking NDT but honestly dont feel any better than when I was meds free.


Shaws you are so right. Levo felt ill on it and was gradually getting worse. Armour finally feel like me again and a proper human being, thyroid is so much about how you feel and less about test results. If only we could be listened too.


It could be that the Levo was just sitting in your blood not doing anything but the NDT is being used by your body, Hence the lower levels. It might just be that you need to keep raising your NDT until you feel better - TSH would then be likely to be suppressed, ft3 top of the range and ft4 mid range or more. I had a TSH of 0.04 on 50 mcg Levo and felt awful. On 0.5 a grain if armour my TSH shot up to 59.0 even though they were supposedly equivalent. Xx


The equivalence charts aren't at all accurate. I should be on 1.5 grains according to the chart but I'm on 4.5 grains and I'm still not quite there. I think this is because the levo gives you how much T4 you need but no T3. I you were to take 1.5 grains you would have the same amount of T4 as the 50mcg levo (roughly) but would also have the T3 you need, if that makes any sense :D It is also probably because it's actually being used, like you say :)


Thanks Carolyn

This has helped me understand I cant really compare one with the other (not in the sense I was trying to do.)

L x


Thanks Clare. That has really helped me get my head round it. I have been beating myself up for not 'getting' it. I think I do now.

L x


Carolyn is tight about the equivalence charts :) Glad to have been of help, sounds like you need to keep raising xx


*right not tight - typing on phone :D


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