What Happens If You Have Excess Iodine?
Are you concerned about your iodine status? Are you wondering what happens if you have excess iodine? In this article we look at the consequences of excess iodine inside your thyroid. We also look at what are the best tests when you have concerns about excess iodine?
Here is What Happens With Excess Iodine
Some of the information is referenced from this review article titled, The consequences of excess iodine. This article has good information with a good illustration. The illustration shows what is thought to be going on when you have excess iodine. Before we jump into the details of that there are a few topics about excess iodine to know about. If you are looking for information on excess iodine, you may be a little bit worried about seeing excess iodine and reading about the problems that can happen.
For the most part, people that have excess iodine levels in a blood test (or urine test), the chances of problems occurring are very very low. However, in some susceptible individuals excess iodine levels can cause issues for your thyroid gland. Iodine in general is very well tolerated and is not going to cause any real problems for most people even when you're consuming levels well above the RDA or other similar minimum standards. Before we look at what happens when you have excess iodine, you need to know how we measure iodine.
How do we determining what excess iodine actually is? How do we measure excess iodine or iodine in general? Blood tests can be used to measure iodine but blood tests can fluctuate a lot based on your iodine intake. Because of this urinary iodine is a little bit better at measuring excess iodine. This type of testing helps us understand when there's excess iodine present since anything that is not used to make thyroid hormone or some other function in your body, is excreted in the urine. When you have normal levels in your urine or high levels in your urine we could be reassured that it's reflecting a true measurement of the functionality of the iodine in your body. What does a high urine level mean?
With high levels excreted in your urine we could assume that there is excess iodine in your body. Anything above 300 micrograms per liter is considered excess iodine on a urine test. Most of the problems that occur with excess iodine are occurring in the thyroid gland.
Thyroid And Excess Iodine
What can happen when you have excess iodine is both hypothyroid and hyperthyroid. These occur through a well-known phenomenon called the Wolff–Chaikoff effect. This phenomenon was described by two doctors from UC Berkeley. The exact issues that occur with the Wolff–Chaikoff effect are not completely understood. There are some distinct things that do happen with this effect and described in the article and here. The normal process that occurs in the thyroid gland to make your thyroid hormones.
When excess iodine occurs in the thyroid gland there's an acute reduction in thyroid hormone production. It is thought that the increased iodine negatively interacts with the TPO enzyme ( thyroperoxidase enzyme). This enzyme is needed to make the T4 and T3 thyroid hormones. Normally the iodine molecules are oxidized and combined together to produce the T4 and T3 via the TPO enzyme. With excess iodine and decreased activity of the TPO enzyme there is less T4 and T3 released into the bloodstream. This leads to hypothyroidism.
Most people are able to adapt to an acute increase in iodine levels. They are able to adapt to this. In healthy people, their body does not take as much of the iodine up into the thyroid gland. Once the thyroid gland has enough it will not take up more and therefore you won't get this excess iodine interfering with thyroid hormone production. Because of this there's not a reduction in the thyroid hormone. Those who already have thyroid hormone issues like hashimoto's, autoimmune, and immune system issues may not be able to counteract those high levels of iodine. Therefore it can lead to the hypothyroidism. This may be transient or in some cases can be more permanent. Failure to adapt to those higher levels can lead to prolonged low thyroid hormone output.
This will mostly occur in those susceptible individuals. Those with low thyroid output already or those with autoimmune things going on. People often have autoimmune thyroid issues occurring and they don't even know it, because it's never been measured. They may not be experiencing any hypothyroid symptoms either. In the presence of excess iodine it could trigger the Wolff–Chaikoff effect and lead to lower thyroid hormone output.
The test to figure out if you have autoimmune thyroiditis is pretty straightforward. It is called the anti-TPO antibody or anti-thyroglobulin antibody. These can both be done through a simple blood test. If both of those are normal, we would expect you to not be as susceptible. We still couldn't rule it out completely but it is less likely.
In some susceptible individuals excess iodine can also cause a hyperthyroid state. Usually this occurs in people with goiters. A goiter is where you have swelling and a broad puffiness in the throat area around the thyroid. The hyperthyroid state has been reported in people that don't have goiters as well.
Sources of Iodine
Now you may be asking, how much iodine is too much? To this end it is important to point out some of the sources of iodine that you may not have thought of. These can cause excess states. In the article above there is a good list of source of iodine from supplementation, diet, medications, etc. I wanted to point out a few of them out here too.
One is a common medication that's used for atrial fibrillation and tachycardia. It is called Amiodarone. This medication contains 75 milligrams of iodine. Given that the usual dose of iodine is somewhere around 150 micrograms and up to 3-5 milligrams, this is a huge amount of iodine. In this case it may be a good idea, if you need to take that medication, to make sure you're not susceptible. In addition there is also some contrast iodine that is used for radiological studies. This can be up to 13,000 micrograms of free iodine which is a huge amount for your body to take in all at once. As long as you're not susceptible it shouldn't be a problem. Still something to keep in mind for those susceptible individuals.
Iodine is an essential nutrient for your thyroid gland to function normally. We all need iodine from our diet. Some people need more iodine because they're not eating the things that are going to give their bodies enough iodine to make thyroid hormone. In the vast majority of people, iodine consumption will not going to cause any problems even at large doses. If you think you might be susceptible to high high iodine levels, you should have a blood test to make sure you don't already have a thyroid problem. If you are considering taking iodine, you might want to do these tests ahead of time to see if you are actually low in iodine.
That should give you a better understanding of what happens if you have excess iodine. If you have questions about the content in this article, please ask it in the comment section below.
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