Thyroid UK
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Could a lack of iodine lower the TSH level?

I ask because I have been re-reading Dr Toftd's little book on the thyroid for the BMA - 1995 edition. In it, he confidently claims iodine deficiency is not a problem in Britain. As a result I can't trust any other claim Dr Toft makes. What he should have said was: "There are good iodine levels in the soil here, and goitre is rare, but no research has been carried out on iodine levels in the population so we don't know whether idodine deficiency is a problem or not." That would be science. The previous statement was ignorance dressed up as fact. Which we all know is common to mainstream medicine.

As most will know, in 2011 Dr Vanderpump tested 700 UK girls and found two thirds of them chronically deficient or worrying low in iodine. Dr V said then that he'd only tested girls, but he thought the whole population might have similar problems. If so, that must change the whole picture for hypothyroidism in the UK.

I've looked at Dr Dach's summary of Dr Yoon's and Reinhard's research on iodine and hypo. Extra iodine doesn't make antibodies go up or down, according to this. It does raiseTSH levels for some people. (Of course they didn't ask these people what their symptoms were). It looks to me as though it might be possible that iodine deficiency could suppress TSH levels. That the rise in hypo cases when iodine is given might be explained by unmasking of the true underlying condition. That the body of an iodine deficient child could get used to ticking away on low levels of thyroid hormones - there would be symptoms of tiredness compared to peers, but nothing too major.

And if so that could explain why so many women in the UK have low TSH and lots of symptoms.

Possible??? Or nonsense??

14 Replies

Aspmama, I think it's fairly recently, in the last 5 years, that UK has been shown to be low in iodine or iodine deficient, so Toft's assertion was correct in 1995. Vanderpump's research suggested cereal with milk was largely absent from the schoolgirls' diet which would have affected their iodine status.

Iodine has been used to reduce thyroid levels in hyperthyroid patients so it does lower TSH.

There is a lot of conflicting research and conflicting views about the pros and cons of supplementing iodine. Too little can cause goitre and low thyroid levels, but too much has been shown to induce Hashimoto's. I believe 150mcg has been established as a tolerable upper limit. Patients on 100mcg Levothyroxine will get 65% of their daily requirement from Levothyroxine and the rest will be from diet.


Thank you so much for replying, Clutter. I respect your view enormously, as you know. But Toft was not correct in 1995, as I explain. The position in 95 was: "we don't know". In 1995, as in 2011, iodine deficiency was a big problem in the UK. It didn't change because of the research. It was there all the time. I know Toft is a sympathetic consultant and on the side of those who have relatively low TSH, but symptoms, and may be helped by treatment. Nevertheless, he is fallible. Here he accepted and reiterated as truth a mainstream view which had no scientific base. He will be doing that on other things.

Vanderpump I think hypothesised the milk explanation. I haven't found the original study (perhaps Humanbean, who is much better than I am at finding stuff, will find it.) But the cutting I have says V. "believes", ie, is not certain, that could be the problem. A research study looking at diet in detail and iodine levels across the UK population, not just girls, especially focused on women, is clearly very overdue.

"Too much has been shown to induce Hashimoto's." But has it though? That's what I'm wondering. Is it possible that iodine deficiency is increasing the TSH in a subsection of hypothyroid people who have , ie, giving them iodine then unmasks an underlying problem? And the scientists are assuming, in a very unscientific manner, that it is causing it because the TSH is rising?

That's how they measure Hashi's, the TSH level, as no one knows better than you, Clutter. Are these scientists making the absolute elementary mistake of confusing correlation with causation? Because they are so fixated on TSH?

The response in hyperT to iodine could be different from the hypoT response. With many nutrients, maybe all nutrients, too much is as bad as too little.

Where I am coming from is - something is very wrong. The symptoms can predate the TSH blood work by years, as you keep saying. I've lived that, so have you, so have thousands on this forum. Either the symptoms are caused by other conditions which eventually trigger a TSH rise, or the TSH measurement is flawed for some reason. I think we could figure it out on this forum. Over 20,000 users..... we know what the answers are. We just have to think hard.


Aspmama, Hashi's is determined by TPOab, TgAb levels or ultrasound scan showing Hashi typical damage to the thyroid. Not all Hashi patients have antibodies and although most Hashi patients will develop hypothyroidism, not all do.

I don't think Toft or anyone is infallible but they can only base conclusions on research available at the time and the UK wasn't designated iodine deficient until a few years ago by WHO. Toft chops and changes his views quite a bit which irritates a lot of people.

The Abstract to Vanderpump's schoolgirl study is here The full article is behind the Lancet paywall.

This study discusses the effects of excess iodine after universal iodine supplementation was introduced in China


yes if you use table salt it is made up of chemical iodine look it up only use Celtic rock salt or Himalayan


Are you in the States? This is a UK forum, and iodine is not added to table salt here. It is in the USA of course. Why do you think it should be avoided?


There's a brand of soymilk - "Bonsoy" - which was fortified with seaweed, leading to cases hyperthyroidism (TSH too low), and kelp tablets/powder are an old folk remedy for weight loss, also due to the iodine.

In the UK a major source of iodine has been the disinfectant used in milking parlours. I've recently found out that the old-fashioned farmer I've bought most of my veg from for the past 15 years has land near the coast and ploughs in seaweed.

Didn't you mean to write "high TSH and lots of symptoms"?


No, no, no. I didn't mean to write that at all. Low TSH and lots of symptoms is the problem for thousands of people whose GPs say they are euthyroid. I'm trying to think why that could be.


The thyroid function tests are incapable of telling where a patient is in regards to their own reference range except at the extremes so a person could get a low result and still by hypo.

What do you mean by 'a low TSH'? Do you mean a 'normal' TSH. PR


Good question. Low TSH with hypo symptoms, sorry, that was impreceise, I mean not high enough to be considered hypo by the medical profession.

So maybe TSH between 1.7 and whatever point your GP finally gives some Levo. Which will vary from practice to practice, judging by this board, below 4.5 at best.

"Normal" seems to me, as used by the medical prof. to be meaningless.


Also, I agree with your statement - what I am wondering is, might a low intake of iodine produce hypo but with a low TSH in some cases.

The assumption of the endos seems to be that though low iodine is the leading cause of hypo, Hashi's is caused by something else, and if anything made worse by iodine. But actually I don't think there is conclusive research on that.

Seems to me iodine levels should be tested routinely when a patient presents with hypo symptoms. And at the very least, the GP could ask: "Do you drink milk?" Which an increasing number of UK citizens won't.

And before pregnancy, what are our iodine levels? It turns out that "Do you drink milk?" is another question we should be asked when turning up with the positive pregnancy test. I look all the time for what might have impacted on my son in the womb to cause his Asperger's/ADD inattentive. A lack of iodine has just been added to my list, along with probably low D, low iron, possible low B12. All the women who are lactose intolerant, dislike milk, are not of northern European descent - in fact the majority - all at risk - I think cows get better pregnancy counselling than humans.


I just took another home test to see has my iodine levels improved and what does my thyroid gland thinks about it.

Was tested first time year ago, being severely deficient with really t3 and high thyroglobulin. Was also lacking selenium a bit.

Will send my samples tomorrow and then have to wait for 10 days. I do feel I need iodine but too much makes me feel hideous. Tho even it improves some of my symptoms it also makes me short of breath. But if I skip it I get nasty coughing.

My tsh has been around 2 and t4 normal so that wise I am in normal range , it is the other numbers wrong.

I am super curious but desperate as well being this ill but in my case it is poor converting I assume. In that case iodine does not do the trick. Been on iodine for 8 months now.


"Was tested first time year ago, being severely deficient with really t3 and high thyroglobulin."

Thanks so much for replying, Justina. Have you missed out a word or two here? Was your iodine severely deficient, and was your Free T3 really high or really low at the same time?

Could you post your results with ranges?


Toft does not believe in T3 in any way shape or form. He has a diabetes specialists' outlook and so should be ignored.


Interesting. Yes, surely research needs to look at iodine status and T3 levels in people with hypothyroid symptoms. So far the whole focus of Dr Vanderpump has been on effects of low iodine status on unborn children, which is obviously v important, but what about the effects on the young girls and women themselves?

What about the iodine status of UK men? Will they turn out to have an iodine status which correlates with the lower incidence of hypo in men?

Why is that simple UK wide iodine level study not being carried out?

How can we take anything the endos say seriously until they do the basics?


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