Switching from Levo to NDT

Advice please... I'm on a very high dose of Levo and want to switch to NDT - as my Levo is high if I follow STTM protocol I believe I will become hypo very quickly.

I don't know whether to lower Levo and add one grain split into 2 doses or stop Levo but take more than one grain? If anyone has had experience of switching from very high dose Levo to NDT please can you pm me ? Thanks

32 Replies

  • The way my doc had me do this a few years ago was to drop small amounts of levo and add in equivalent amounts of NDT. I think she had me swap 1/2 grain for 25 mcg T4 every 7-14 days. You could go for a whole grain but the extra T3 could be difficult to handle at first, thus the suggestion to start with 1/2 grain. I did quite OK on this and didn't really notice any side-effects except for some shaking in my hands (which comes back any time I go on T3). Good luck!

  • Thank you 👍

  • Just working out the maths so in your case your doc was equating 1 grain to 50mcg t4?

    Was that being cautious ? Or was that about right allowing for the t3?

  • Yes your maths look to be right. I have no idea if that equivalency is cautious or not - I have read about various different conversions...

    i think i read on this forum some people saying 1 grain = 100mcg T4 but I personally think 1 grain is much less than 100 T4. The math wouldn't work out anyway. Since NDT has 38 mcg T4, the remaining T3 in that 1 grain would give a potency of 7x that of T4, to get up to 100 T4.

    That is, 1 grain = 38 T4 + (9 T3)*(7) =~ 100 T4. I doubt T3 is 7x as powerful as T4.

    A more reasonable conversion IMO is

    1 grain = 38 T4 +(9 T3)*(3) =~ 65 mcg T4

    The real problem is that no one knows how the T3 will affect them, so it's quite possible to need a totally different dose of NDT compared to Levo, even if one knew the exact potency of T3 compared to T4 and could compute the exact equivalencies. So I would see these more as starting guidelines. STTM says to raise to 2 to 3 grains and then test after 6 weeks - you could swap over until you get to e.g. 3 grains, drop the remaining levo, and see how it goes.

  • The manufacturers tend to suggest 1 grain as replacement of 100 micrograms of levothyroxine. I interpret that as a cautious calculation intended to avoid anyone overdosing if they switch over at that rate.

    (This also means anyone switching BACK to levothyroxine had better be careful!)

  • Thanks that's good to know - so I think then I can drop 100 and add 1 grain relatively safely if it's a cautious calculation - I'm on such a high dose of Levo this is really the only way for me to switch. Thank you !! 👍

  • good luck :)

  • What dose are you on? I'm very confused with the grain to mg thing, never heard the dose to be in grains..

    My boyfriend takes 100mg of levothyroxine per day, he wants to change to dessicated thyroid but we have no help from the GP or the specialist none of them seem to know what they are talking about!! Tony isn't any better since taking the levo for the past about 16 months, in fact he is much worse.. Continually looses weight, 1 and 1/2 stone in 10 months, maybe 2 now as he hates weighing himself.. Doctors just say can't understand why you still feel ill your levels are fine etc.. When Tony asked for dessicated thyroid they'd never heard if it and said definitely couldn't prescribe it.. I've found so wine on here that gets erfa thyroid from a reputable chemist in Andorra and they sell it without prescription, she says its legit and she has used it for a long time.. What dosage should Tony start off with and should he start off gradually introducing erfa taking erfa and levo and gradually reducing levo..??

    I'm at my wits end with all this, his ill health and getting no medical help can someone please help.. Any help and advice greatly appreciated, thank you..

  • If your partner is on 100mcg Levo that's roughly equivalent to 1 grain I say roughly as it isn't easy to directly compare but if he is losing weight it does t sound like hypo have a look at the list of symptoms of both hypo and hyper. Good luck.

  • Ah OK, I was wondering where those numbers came from. thanks :)

  • From here, for example:


  • I wish there was an "unlike" button ;)

    So insane, no one who takes 3 grains was previously on 300 mcg T4, nor likely would have been able to tolerate such a dose. Such a shame too that this comes from RLC labs!

  • About to do the same myself and I have asked for advice too! I currently take a high dose of Levo but I remember reading start with 1 grain for 2 weeks before slowly increasing. I'm just waiting for some confirmation. Good luck with the switch!

  • Pm

  • I don't understand what a grain dose is.. He's on 125mg levothyroxine per day..

  • A grain is a traditional unit of weight. It is between 60 and 65 milligrams.

    He will be on 125 micrograms of levothyroxine. (Not milligrams.)

    Desiccated thyroid is produced in tablets of one grain (and in some makes, multiples of that). They sometimes say 60 mg, sometimes 65 mg, sometimes one grain. All are very much the same thing.

    Desiccated thyroid is manufactured and dosed by weight of dried thyroid powder contained - NOT by the thyroid hormone contained.

    Levothyroxine is by weight of actual thyroid hormnone contained.

    It is absolutely vital that you understand this and do some reading before making any changes.

  • As far as I know when switching from levo to NDT you can do a straight swop-over, i.e. 100mcg of levo is roughly equivalent to 1 grain of NDT.

    If all your clinical symptoms resolve you remain on the dose but if symptoms start you increase dose by 1/2 grain every two weeks until you are symptom free. (I prefer increasing by 1/4 when you feel you are nearing your optimum dose). If pulse or temp increase too much, reduce to the previous dose.

    (I am not medically qualified - have had undiagnosed/unmedicated hypothyroidism but am now well on T3 only). I also tried other alternatives.

  • Thank you.

  • I would beware of switching directly. I did that and went hyper very quickly. I wasn't converting and so I got a huge rush of T3 which was great for a day or so, and then everything started to jitter.

    The gradual approach is going to be a lot safer. Hopefully you won't need a huge dose of NDT and if you go gradually you can fine tune much more easily.

  • So to avoid that presumably you could reduce by 100 mcg Levo and add in one grain and see how you go? Split in two doses ?

  • That seems the most sensible. Then if you feel yourself going hyper you can replace the next 100 with less NDT. It took me about a year to work out my optimal dose. And some winters I increase slightly.

    I don't split my dose. Tried it, made no difference, and too easy to forget the second dose.

  • Ok thank you I think I will do that as if I try to stop Levo and start on 1 grain I know I will crash.

  • Thanks for your support back when I started NDT having just read about winter - it's freezing - and wondering whether I could do with a tweak reading your post has reminded me. Btw I've been doing great on NDT over Levo - switched over by weaning off Levo thank you! 👍

  • What are the symptoms of a hypo or going hyper?

  • There are over 300 symptoms associated with hypo, probably as many for hyper! There's a fairly comprehensive list on the ThyroidUK website IIRC,

  • Try dropping the levo altogether for a couple of days then start on a low dose of NDT it works! I felt amazing even on a low dose.

  • I can't do that - I'm on a very high dose Levo so if I do what you have suggested it's highly likely I will crash. But thank you for taking the time to reply to me.

  • I was on 175 mg of Levo I stopped that and the next day started on 150 of Thyrogold. I had no problem switching this but then made the mistake of increasing too quickly.

  • How did you get on with that product after? I have considered that one and have emailed Tammy.

  • I am still on it. Initially I got all sort of side effects, ( itching skin, aching joints, tunnel vision, palpitations) I think because I raised too fast or may have been a reaction to the NDT itself. But they have all subsided. I feel more energetic, I have a clearer brain. My anxiety and depression have got better, and I have started to lose weight. I think that it's a case of trial and error. Some people prefer WP or Amour and don't like Thyrogold. have you deceieded which one you will go with?

  • I've got thiroyd ... Haven't started it yet but got as was cheap. Looked at naturethroid and thyrogold too ... Will prob get one of those but have to pay customs duty on both brands .. Think will try thyrogold as some people seem to do well on it.

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