What to do when supplements change thyroid levels?

After supplementing with B12 and selenium, my B12 went a little too high and I found I was getting overactive thyroid symptoms including raised blood pressure and pulse. I'm not sure if it was anything to do with the supplements but nothing else showed up in blood tests. My FT4 was a little over range at 24.6 (12-22). Taking 117 levo. I don't have antibodies.

After stopping supplementing B12 and selenium for 4 months, I'm now getting hypothyroid symptoms (I think they're hypo symptoms) of cold hands, morning temperature not reaching 36.0. My temperature is consistently 35.6 - 35.8. I've got dry skin and my memory is not quite so sharp but otherwise feel ok. The labs won't do FT3 here.

Serum TSH level 0.11 ( 0.27 - 4.2)

Serum free T4 level 20 pmol/L (12 - 22)

So what is best to do?

1) Should I pay out to get B12 and thyroid bloods done privately to include FT3 and then decide what to do?

2) Should I begin to supplement B12 and selenium again?

3) Do I simply increase my Levothyroxine to combat the hypo symptoms?

I don't want to pay for unnecessary tests but I don't want to get ill either. All other vitamins are in good range including vitamin D which is mid-range as is the prevailing advice. I'm now on a maintenance dose. Ferritin also mid-range. Folate was high at last test.

Any suggestions about which course of action to take based on your knowledge or experience?

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16 Replies

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  • Nanaedake,

    Improving nutrient deficiencies can improve Levothyroxine absorption and conversion of T4 to T3.

    TSH 0.11 and FT4 20 indicate you are adequately dosed on Levothyroxine but without FT3 it's not possible to see whether you are converting well. If you want to check conversion you need TSH, FT4 and FT3 tested at the same time.

    4 months after stopping B12 will give you a baseline result. I think it may be worth ordering a private test to include TSH, FT4, FT3, B12 and folate.

  • Ok, great I'll do that then. It would be really useful to have a baseline so worth paying out for.

  • Nanaedake,

    Medichecks do #ThyroidThursday discounts. Probably cheapest to get the UltraVits package thyroiduk.org.uk/tuk/testin...

  • Ok, thanks, I've had a look at it before, so could take that option.

  • Nanaedake, I'm in remission from Graves and for a while because it was only just into the range and although my endo thought that was ok, I didn't so I started taking sublingual B12 every day - at one point my B12 was way over the upper limit 1269 (142-725) I've cut back on the B12 but I can't say I noticed any difference in how I felt whether it was sitting nicely in the middle of the range or when it was totally over the top.

    I pay to get my bloods done a couple of times a year, my area doesn't do T3 even when it was requested by my endo, nor do they want to test for antibodies, vitamins and minerals, so I do my own. When my B12 was very high I cut back and now I just take it every now and again, sometimes I'll have a week a month taking it and sometimes I'll take it at weekends - and I know that's not very scientific but if I take it every day it would be far too much.

    What clutter says makes lots of sense - get everything done and have a baseline.

  • That's interesting that you found no difference with B12 supplementation mid or over range. The other possibility is that one batch of levothyroxine was much stronger than the next batch. I'll have a better idea when I get the bloods and know where my B12 and folate level is. If I don't need to supplement B12 or folate then I could supplement with selenium again and see if it has the same effect. If nothing changes I'll know it's the levothyroxine causing problems again.

    Thanks to you and Clutter for your advice.

  • I also over cooked my b12 went from 200 to over 1700 just by changing to sub lingual. I have cut back and on last test had dropped to 1300. I felt rubbish at 200 but had bad vitd too. Vit d is responding slowly but feel quite good, no adverse feelings with well over top b12 and no difference dropping to 1300 either, just need to figure out dose to get it to stabilise around 1000 which seems to be the current recommendation

  • ok, thanks, that's great to know. I'm thinking now that I had a batch of levvothyroxine that was stronger than the previous one and it caused me to be a bit overmedicated. I'm still learning to recognise the symptoms of over and under but it's tricky if levo batches make such a difference. How to maintain stability is a constant challenge.

  • It may not even be the strength, it doesn’t take much to affect absorption, a minor timing or eating change you hadn’t really thought about could be enough if it becomes regular or if you normally exercise well but cut back or stop for some reason. Both could have the effect of a small dose raise if done for a while (like during the summer)

  • I've been wracking my brain. The only thing I can identify that changed is the hotter weather and I was drinking more water so more hydrated. Could it really make that much difference though?

  • PS Im like you, no antibodies, to my mind that makes it even harder in some respects, thyroids don’t normally fix themselves but if we don’t know why ours broke in the first place, maybe yours was having a good month and decided to put in a bit more effort.

    Alternatively, how many antibody tests have you had and was it for both types, you may have had a hashi flare after all but just not raised at time of test, Ive had 4 barely detectable ones so think Im safe to say negative!

  • I've had 2 antibodies tests and one when I felt overmedicated but no antibodies. I had a partial thyroidectomy as a result of thyroid cancer. Well it's tricky because if remaining thyroid keeps putting in an extra effort then how do I stop that from happening and how do I keep it on an even keel? Maybe it's like having Hashi's without having Hashi's if you see what I mean but there's no end in sight because remaining thyroid isn't going to eventually die. Docs don't seem to know anything about it or ever come across it so no-one seems to be able to explain what's happening.

  • What you say is interesting as I also had elevated B12 levels a few months ago, along with some hyper symptoms, FT4 levels above midrange and FT3 levels above range (I take NDT so my TSH has been suppressed for years; also, when on NDT, your FT4 levels should ideally not be higher than midrange as NDT also contains T3). I did not know it was possible to overdose on water-soluble vitamins such as vit B as the body supposedly flushes them out, and I never made the connection between my hyper symptoms and elevated B12 levels back then...I have since cut back on B12 as well as NDT, and now feel fine. But I agree with what others have said; first of all, try to have your FT3 levels tested. But your TSH looks fine, as do your FT4 levels. If you feel fine on your current dose, it's likely you are a good converter.

  • I don't think you can overdose on water soluble vitamins because your body does clear what you don't need but you could overreplace and it might take a while to clear. I think the only problem would be if a person had kidney disease and kidneys weren't clearing everything properly. If you have a good level of vitamin B12 I wondered if it was possible that it made your thyroid more efficient and therefore thyroid meds more effective but I really don't know. I'm just trying to figure it out. I will get blood tests as suggested.

  • Selenium is needed for T4 to be converted to T3. It sounds like you ar4e low in it, so when you stop it, T4 just pools and looks too high, but you feel worse as you are not making enough T3 from lack of selenium. I would get a FT3 and FT4 test and if FT3 is low, go back on selenium and B12 to improve conversion.

  • OK, good thoughts, thank you.

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