Why does ferritin have to be high for NDT but not for Thyroxine?

I have been on Thyroxine for years but want to try Nature Throid, as I think it might be better for me, as it contains calcitonin. However, I have noticed that lots of people here suggest getting Ferritin levels at least 70 before starting. I have low Ferritin, and just below mid B12. If I'm already taking Thyroxine on these levels, and surviving, what's the difference between taking Thyroxine and NDT when thinking about Ferritin levels? what difference will it make? Will there be a different reaction, and why?

25 Replies

  • Katyabat1,

    All thyroid meds work better when ferritin is optimal but some members seem to think they won't work at all when ferritin is low. There's no reason why you shouldn't switch to NatureThroid while ferritin is sub optimal.

  • Dear Clutter

    This is really useful! I saw some threads on other forums where people were reporting terrible reactions to T3 and NDT to do with Ferritin levels being low, or so they seemed to believe, but I think with this understanding of the different points of view I feel stronger to just have a go! BTW, how much iron should I take do you think to get my ferritin levels better?

  • Katyabat1,

    Some people do have difficulty increasing dose when ferritin is low and may feel hyper and hypo at the same time.

    What is your ferritin result and range?

  • Dear Clutter: here are my results:

    Ferritin 23.30 in a range of 10-300

    B12 440 in a range of 200-950

    Iron 86 in a range of 50-170

    Vit D 34.90 in a range of 30-100

    Folate 15.27 in a range of 3-20

    Perhaps if I change gradually from Thyroxine to Nature Throid these symptoms from increasing won't potentially occur?


  • Katyabat1,

    Ferritin is optimal halfway through range. Supplement 2 or 3 x 210mg Ferrous Fumarate and take each tablet with 500-1,000mg vitamin C to aid absorption and minimise constipation. Take iron 4 hours away from thyroid meds and retest ferritin in 4-6 months.

    PA Society say B12 is optimal around 1,000. Supplement 1,000mcg methylcobalamin and take a B Complex vitamin for the other B vits.

    Folate is fine.

    What are the vitD units in Italy? In the UK <75nmol/L is sub optimal.

  • Hi Clutter

    Thanks for all this info. I bought Iron Bisglycinate 214mg and got very bloated- what do you think, and every one else, of Floradix, which suggests 15mg a day, perhaps taking more than suggested? I suppose I would have to drink half the bottle to get what I need!

    I was taking Swanson Super Stress B complex which has 125mcg of B12 in the form cyanocobalamin but it seemed to make me depressed. that was already 2000 % of the daily value necessary- so 1000mg seems extraordinarily high. But is the other format -methylcobalamin-a better one?

    As for Vit D, those were the reference ranges for Italy on the print out. I am currently taking 5000 IU Vit D.

    Also taking K2 (500mg with mk 7 100mg) and Selenium 100mg and zinc 32mg and copper 2mg

  • Katyabat1,

    If you can't tolerate Iron Bisglycinate which is quite gentle on the gut try Floradix. It will simply take longer to raise level.

    1,000mcg methylcobalamin is not a high dose. Most people will find methylcobalamin is better absorbed than cyancobalamin.

    If vit D is measured in ng/ml 40-60 is optimal. 5,000iu daily is fine.

  • Hi Clutter

    Yes it is measured in ng/ml so I'm getting there.

    In terms of iron, once you start supplementing, does it just build up gradually? Does that mean it's difficult to get rid of if you take too much? One day I took an iron tablet and then some Floradix by mistake and got a terrible headache and very exhausted which is totally out of the norm for me.

  • Katyabat1,

    Iron builds up very slowly over months. 1 iron tablet + Floradix is not going to over medicate you. If your iron levels go to high levels will drop after you stop supplementing.

  • Actually its THYROXINE usage that requires




    Vit D3

    all to be halfway in their ranges because without that your body is unable to utilise the Levo T4 and convert it into the T3 that every cell in your body needs

  • Hi there Reallyfedup! Well, my levels of Ferritin are very low, so I'm wondering how I'm able to survive? I'm pretty active and have good energy levels. Do you think my adrenals are over working with Cortisol to compensate? I did get a test done and they were pretty high!

  • There's a difference between surviving and living.

  • I've just bought Ferrous fumarate 322mg on eBay. 3 boxes of 28 pills for £5.50.

  • I would be interested to know how you get on with them! :)

  • Sure thing. My ferritin was 48 about a month ago. I've been taking 28mg of iron for the last few weeks, plus I've bought a Lucky Iron Fish! 💪🏻🐟

  • Ooooh! What's that? I think I need one too! :) My Ferritin level is half of your one (23!)

  • Really cool idea - luckyironfish.com

  • much better to buy Blue Bonnet Chelated Iron on Amazon

  • why is that one better?

  • When any substance is chelated its absorption by the body is easier

    Many people find ferrous fumeraste difficult to tolerate

    Buying on ebay may also be dodgy

  • that's really useful to know!

  • My ferritin levels were low when I started on NDT and I was concerned too but I've had no problems. I have been supplementing with Solgar Gentle iron and after my last ferritin test last week my levels have increased significantly so I would recommend them x

  • Dear Natchap that's useful to know! were your levels as low as mine and how much NDT do you take?

  • I believe may people find that because NDT is a complete hormone the bodys need for ferritin is less and the low ferritin problem sorts itself out as the body heals

  • thats also very useful! I got a bit freaked out with all the horror stories of people needing to get their ferritin up before starting- not on this website, but elsewhere.

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