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Thyroid UK
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high urine iodine

Hi, I have been wondering why I have high urine iodine 240ug/l

I had a chest scan which used radioactive iodine 6 months ago and I assumed it was due to that still coming out of my system, although from what I can see in research materials, it should be excreted much quicker than that. Anyway, read something today which informed me the the NDT I am taking has iodine in it. I just found some other information that analysed the quantities in an NDT product and it seems that 3 grains a day, my dose, will give 3/4 of the daily recommended amount. This iodine is apparently in addition to any iodine that is bound to the T4 and T3 . stopthethyroidmadness.com/2...

So, is dietary iodine excreted if you have too much in a day or is it stored? If it is not stored then the amount in my urine is either due to excessive amounts in the NDT or I am till excreting the iodine from the radioactive iodine, perhaps due to poor detoxification? Or both.

So, I guess the question is, should I be taking NDT at the moment if it is giving me extra iodine, which it seems I don't need, based on my urine sample? Does anyone know anything about this riveting aspect of hypothyroidism :-)

Thank you :-)

14 Replies

Thyroid hormones, natural or artificial, NDT or T3 or levothyroxine, are molecules made up of several atoms. Amongst those atoms is iodine.

T4 is called T4 because each molecule of it contains 4 atoms of iodine.

T3 is called T3 because each molecule of it contains 3 atoms of iodine.

You can't have thyroid hormones without iodine. If you removed the iodine from any thyroid hormones they would no longer be thyroid hormones...


Thank you,

yes, I understand that but there seems to be evidence that there is also additional iodine knocking around in the NDT, which would not be in levothyroxine because it is the isolated T4; or have I misinterpreted the data from the link I posted? Is the iodine content they refer to, the bound iodine? perhaps, will have to look at it again.


There are lists of ingredients for some of the NDT brands on this page :


I can't see any evidence of fillers which contain iodine in any products currently being made, but then I'm not familiar with a lot of them.


Great, thanks. I take thyroid. I'll have a look :-)


You might find this link useful :


If your iodine levels worry you perhaps you could reduce the number of iodine-containing foods you include in your diet.


Hi again, thanks for the link, interesting. :-) I am unlikely to be having too much iodine in my daily diet based on that information.


My iodine is sky high, too. And I'm not taking iodine, and don't eat high iodine foods. I do not believe that excess is all excreted. But, I don't think it's doing me any harm. Don't know, really...


Thanks greygoose, that is my situation too, regarding intake.

240ug/l is, I think, the same as 240mcg. The recommended daily dose is more than this amount so I don't understand why it should be classed as too high and "danger of overdose". What is your level? was it a urine sample? I just did some googling and although there is some disagreement, 70-80% of iodine is stored in the thyroid gland, so this seems to mean that it is sitting there, waiting to be utilised as part of T4 when it is produced. This means we do store it to some extent. Maybe someone else will chip in who has more info :-)


Actually, I don't remember, it was a long time ago I had it measured. But, I had practically no thyroid left at that time, so I wasn't storing iodine in it. It was just the iodine from the 6 grains of NDT I was taking. I had it done because my doctor wanted me to supplement iodine, and I said, I ain't supplementing nothing without getting tested first!

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Interesting, so you had sky high iodine from taking 6 grains which apparently, very approximately, gives the recommended daily iodine dose. The mystery deepens.

The reason I got tested was because a private doctor wanted my daughter to take iodine, without testing whether she needed it. I said not until we know she needs it. We were both tested; she needs it, I don't.

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You might find this link about iodine testing interesting :


It might not be relevant if you just did an ordinary iodine test rather than a loading test.


Yes, thanks. I had a read through and interestingly, of their participants , 2 had iodine levels in the "danger of overdose" range and 1 had a much higher level- all before the test was conducted. It does make my 240 result look not that much of an issue... who knows


I've been wondering about iodine recently too sue_b. I had a simple urine test two years ago through Genova which showed marginally low iodine, I was taking 2.5 grains of ERFA at the time. I decided not to supplement because I wasn't that concerned.

A few months ago I did another urine test, using Biolab, which came back as 886mcg/L with an upper optimal range of 199 and "risk of hyperthyroidism" above 299. I was certain it had to be wrong, so did another, this time with Genova again so that I could compare with the original one two years ago.

This third one came back at 203mcg/L with an upper optimal range of 199 again. The only difference is that I've been taking 2.5 grains of Thyroid-S for the last 22 months, and for some of that time I even reduced the dose.

All I can think is that different brands of NDT might have more easily absorbable iodine (if that's even possible) or that the body alters how it processes it. I think that your level, given the ranges on my results, is probably within the "More than adequate" range, rather than the "Excessive" which is anything over 299.

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Thanks Framboise,

That does shed some light on it all. How could your two tests be so different? On the face of it, it seems that variation of that ilk could only come from your dietary intake in the 24hrs or so before and during the test time period. I say this based on the two links that humanbean posted and the fact that your two tests were close together and I presume, the absence of a supplemental change .

The first link has info about the levels of iodine in certain foods. It is conceivable that if you ate enough dairy produce in a day you could have an output of 885mcg/l as the second link, about tests that were done to ascertain output after a specific dose was given, shows. With my limited grasp of the data, it seems that the body does excrete the majority of excess iodine fairly rapidly. The variation between excretion rates in the research does not seem to have a relationship with the levels of urine iodine that were taken before the high dose was administered. Some people had similar excretion rates but had very different starting points, this does imply that something else is a factor. It seems then, that unless you are having large amounts all the time and for some reason cannot excrete it, excess shouldn't build up. Likewise, if there are no absorption issues, you shouldn't have a deficiency unless you are vegetarian/vegan and don't supplement the iodine.

It does seem odd then that iodine deficiency is, apparently, pretty common, or is that just in America, where their soils lack iodine? Apparently, my daughter needs to supplement at the moment or perhaps it was just that in that particular 24hrs, her intake was low. There is the issue about selenium levels being adequate, not sure whether that has some implication as to whether you absorb iodine adequately. Brain fog has arrived, hopefully some ability to think will return :-)

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