Levothyroxine to NDT switch

I have been on Levothyroxine 150mcrg for years and am making the switch to NDT finally! My endo told me to stop taking levo and just go straight to 120mg (two tablets) of NDT at once. I am happy to see how I go, however I am little worried about my low iron levels as I hear this may cause complications. My ferritin is 9, but haemoglobine levels are good. Do you think this will be an issue? Also, from your experience, would you go ahead and switch at once or do it more gradually? Thanks a lot!

28 Replies

  • PastelOak Have you got the range for ferritin? It should be at least half way through the range and 70 is usually the minimum recommended for thyroid hormone to be able to work. Is 'haemoglobin levels good' the doctor's opinion or do you have the actual result. My iron panel came out pretty good but my ferritin level was only about 20% through the range.

    Sorry, I can't help with switching from Levo to NDT.

  • Thank you for your reply! The ferritin range is 13.00 - 150.00 if/L (I am at 9), and according to another test I'm at 8.9ng/ml (range 6.24 - 137) so looks like it is quite a lot under the ideal levels? Haemoglobin is at 130g/L (range 115 - 165) though. How do I get the iron stores up? I'm takin iron supplements and eat healthy, but for years I have had the low ferritin levels now, so not sure what to do.

  • PastelOak My haemoglobin was 136 (115-165) last October yet my ferritin was 35 (13-150) so not as bad as yours.

    With a ferritin level below range, and the other only just inside range, I would have thought your GP or endo would be giving you iron injections.

    I have great trouble with iron supplements, even taking just 5mg ferritin supplement, but constipation is a major problem regardless of what else I take to help. I am now eating liver about once a fortnight and will see if that helps.

  • Sorry to hear you struggle with your iron levels too. My doctor actually also recommended eating beef liver to help boost my iron levels, might have to give it a try!

  • PastelOak Ther's good iron content in chicken liver, I've never tried it, I have only had lamb's liver. This is a table of foods with iron content and pork liver is highest healthlinkbc.ca/healthfiles...

  • PO,

    I think low iron might be an issue when starting NDT ...

    .... but if you decide to start NDT, your endo's starting dose of 2 grains is more than your Levothroxine dose so you may need to start slightly lower as your body needs time to adjust to the T3.

    The starting dose shouldn't be held for too long as there is a normal suppression of the feedback loop between the hypothalamus, pituitary and thyroid gland meaning less messenger hormones are released making you even more hypothyroid than before you started NDT.

    Less thyroid hormone will mean a higher TSH and so possibly higher antibody levels giving more chance of a Hashi attack ( if you have Hashimotos..) ...

    Some members find it difficult to raise NDT with low iron and after an initial good period become symptomatic after about 5-6 weeks. If this were me I would medicate T4 & T3 (which appear more sympathetic to deficiencies) until iron levels were optimal.

    You can stop Levo and start NDT the very next day.


    Low Iron & NDT.




  • Thanks for the response radd! I also thought the dose seemed high to start with. Although according to the enso and some of the conversions I found online, it is actually lower than my current levo dose! This is not Armour NDT but another brand of NDT, I wonder if that makes any difference. The low ferritin does worry me, but I am not sure how to replenish the iron stores as this has been the situation for a good while.

    You mention that you would medicate with T4 and T3 as this is more sympathetic for deficiencies - do you mean NDT, or Levo + T3?

    I think I will start with NDT, but not sure if I should start lower as many of you suggest or go with the endo's prescription. Confusing! But happy that things are moving along and that at least I have gotten my hands onto NDT.

    Thanks for your help!

  • PO,

    Yes I meant synthetic T4 & T3. This also allows you to introduce your body to T3 more gradually by using smaller doses as T3 can be felt powerful to a body totally deficient in it.

    I don't supplement iron so can't recommend but some members seem to favour Ferrous Fumarate taken with 500mg-1,000mg vitamin C to aid absorption and minimise constipation. You can always repost a question re iron supplements or use the search box above.

    Consuming dairy products, coffee, tea, chocolate and eggs with iron can interfere with the absorption.

    Good luck with NDT.

  • Thanks for all the help! I took my first dose of NDT this morning, 1,5 grains which works out about 90mg NDT (1 grain = 60mg). I didn't take Levo at all. Do you know the conversion for NDT (Greater Pharma 'Thiroid')? Just wondering how to compare it to the Levo dose (150mcrg) I have been on. There seems to be different conversions around, some higher and some lower.

  • 2 grains is high to start. I find it better to split the dose say 1 grain early AM and then 1/2 grain late morning / midday

  • I've switched - it's a bumpy ride but it's worth it! I followed the STTM protocol which advises starting at one grain, split morning and afternoon. Then add half a grain every 10-14 days, or when you feel symptoms returning. Eventually you'll find you have no hypo symptoms around 2 or 3 grains a day. Then get your bloods checked - you should aim for optimal results. On NDT your TSH should be around 0.5, FT3 in top quarter of range and FT4 mid range.

    I'll post the links to the guides, or there's a couple of really good FB groups you could join. StopTheThyroidMadness of course, and FTPO (For thyroid patients only)

  • Thanks for your response and the step by step advise Michelle! I think increasing like this sounds sensible. Would you ditch the Levo completely from the start, or take both, increasing NDT while lowering the Levo dose? I might try to take a litter lower dose NDT at the start. I was thinking of stopping the Levo completely like others here and my endo suggested.

  • STTM protocol says to stop Levo the day you start NDT

  • I was on 150 my endo started me on half and I really struggled increasing every 2 weeks and he stopped level immediately. I would start on 1go no levo and increase every 2 weeks or a after week to 1.5g if you are really struggling but then wait at least 2 weeks before increasing again. I am now on 3g if that helps but it took 4 months to get there. Stick with it it is worth it.

  • Thanks wedding2000! It is promising to hear about your journey and how you now feel better. I was wondering what kind of symptoms you may have had when you were starting with NDT?

    I have swapped my Levothyroxine 150mcrg to NDT 1,5 grains (90mg) which I have been taking in the morning for 5 days now. I have to say I haven't experienced what I was expecting - certainly no more energy, or no heart palpitations or other hyper effects which I was kind of anticipating to have.

    Instead I have had very strong hypo like feelings; complete lack of energy, feel difficult to move, slow like a sloth, grumpy, very tired and sleeping for hours.. Is this because the dose is still low compared to what I need? Or does my body not know what to do with T3? Is this normal, or am I doing something wrong? I also worry that this could have something to do with my low ferritin levels - I wonder what kind of symptoms does that cause combined with NDT newly introduced to the body?

    Not quite sure what to do next.. I was planning to increase to 2 grains (which my endo actually recommended as a starting dose, but I felt I wanted to start from little bit lower at 1,5..) but now I don't know if my worsened being is due to the new medication or the lack of it!

    Any help or ideas would've highly valued. X

  • I personally would increase now as it has been a week. My symptoms were different many extreme fatigue and pain in lymph nodes swellings levo wasn't converting to T3 for me and some reason caused this. If you click on my icon you can read my full history and others on their pervious posts.

  • I assume you are treating low ferritin Levels? Sorry I don't know too much about that and symptoms. Good luck stick with it. I didn't start to feel well again until on 2.5g.

  • Personally I stopped levo for 2 weeks before starting NDT as levo is a storage hormone and can stay in the system for up to 7 weeks! Start on a low dose of NDT DO NOT do a direct swap as it rarely works. The T3 will be far too uncomfortable for your system. Sometimes I think doctors say to do a direct swap so they can say they ruled NDT out!

  • Thanks Glynisrose! Do you know what kind of symptoms or feelings one might get after starting on too high dose of NDT? I have swapped my Levo to NDT in one go 5 days ago, but have been taking a slightly smaller dose (1,5 grains, or 90mg) than what the endo recommended (2 grains, or 120mg). I feel rather unwell with the worst kind of hypo symptoms, extreme weakness, tiredness etc. Am I taking too much or too little?

  • Did they check your levels of vitamin d and b 12 ?

    Do you have Hashimoto's? If so, are you gluten free?

  • Hi SlowDragon, yes vitamin D was tested and it is very good apparently at 108 (I don't have the range though) and vitamin B12 looks good too at 444ng/L (range 190 - 660ng/L) don't you think? I don't have Hashimoto's as far as I know, all thyroid antibody and celiac antibody tests have been negative. I eat gluten. Perhaps I shouldn't.

  • PastelOak Your Vit B12 isn't very good. It may seem to be at the better end of the range but apparently anything under 500 may cause neurological problems. Pernicious Anaemia Society recommends 1000. You could do with supplementing with Jarrows or Solgar sublingual methylcobalamin lozenges and take a B Complex as well to balance the B vits.

  • Thanks a lot, will try these supplements in order to take care of my vit B levels!

  • My ferritin was also low. 8.8. Usually they want to do a million tests to see if there's a reason why as ferritin levels can plummet as a defence against illnesses. Assuming that isn't the case , as someone else suggested ferrous fumarate is preferred to get your levels up but it's a v slow process. They told me 2\day for 12 weeks and re text then to see where the level gets to. Also be sure to take 4 hours away from thyroid meds.

  • Thanks Olsbird, I am veggie and have heavy periods, and have also been medicated with synthetic T4 for over 15 years, so I guess those all add up to my low ferritin levels.. Willing to try some liver to boost up my iron intake, as the tablets seem to be taking ages to have any kind of effect!

  • Don't suppose your endo is in Thames valley or London by any chance?

  • I can't remember exactly when I did the increases but I just stopped mindful that I had a store in me of the Levo and started with galf a grain split as I'd heard so many had problems getting used to the T3 addition. I then raised it as it felt necessary to do so. I did take it more slowly than suggested and I did have a slight dip I felt which must have been when my stored Levo was out of the system. My main problem was remembering the afternoon dose so I then took it all at once and that worked for me! I did overshoot a little but realised I had felt better on the way up so tried lowering the dose a little and that worked better. I'm now only taking 1.75 and that works well for me but I have also added in a few more supplements along the way which I presume must be working better for me. Going hyper isn't pleasant so take things slowly and don't go to mad with your extra energy let your body and life style adjust and you should be fine. Shout out if not or any concerns and I'm sure you will get plenty of help.

  • Thanks silverfox for your kind response! I have just posted a couple more questions up in this same conversation, as feel that I have a somewhat negative response to my NDT trial so far.. Have very bad hypo like symptoms of extreme tiredness, sluggishness and feeling very weak, and not sure if this is my body saying I am getting too much T3 too fast, or perhaps too little? I'm taking 1,5 grains which is 90mg. The endo prescribed me a bigger starting dose of 2 grains (120mg) but I wanted to start lower. This is my 5th day on NDT and I have felt like spending most of my day in bed.

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