[Anonymous]

#1050509

Can someone please explain to me the connection between iodine and Grave’s disease? I know that the thyroid metabolizes iodine, and I know that a Grave’s thyroid will absorb iodine more quickly. Do other hyperthyroid conditions not result in this speedy absorption of iodine (i.e., is this the reason for doing the I123 uptake test — to distinguish Grave’s from other hyper conditions?)

What does the thyroid convert the iodine to? Why is it bad to have too much iodine? Does too much iodine in the diet lead to more production of thyroid hormone? And if it is bad to have too much iodine, should we all avoid iodized salt? Is there a way to know whether processed foods contain iodized salt or regular salt? If not, should we all be going on a low salt diet?

[Anonymous]

#1149425

Hi, Kathleen:

Wow, you packed a lot of questions in a short post!! ; )

OK. The short course on iodine. Perhaps not in the order you asked. The thyroid takes in the iodine and eventually turns it into thyroid hormone. There are two thyroid hormones, basically, whose short-hand version names are T4 (because it contains FOUR atoms of iodine in it) and T3 (because it has THREE). Because the thyroid is the only organ/gland in the body that absorbs iodine, the uptake and scan test can be used to find out if the thyroid is too active (i.e. absorbing too much iodine too quickly), and to help figure out WHY it is too active. There are several different possible causes for being hyperthyroid. Graves is the most common, but there are others, and sometimes the way the thyroid LOOKS after absorbing the radioactive I of the test gives the doctors clues. In Graves’, the whole gland will show uptake, whereas in other possible hyperthyroid conditions there will be specific, localized spots where the iodine was taken up faster than in other places. This helps the doctors figure out what type of treatment might work best to get rid of the hyperthyroidism. It is as important to know WHY because treatment options will vary. Some conditions that cause hyperthyroidism must be surgically removed. Some conditions that cause hyperthyroidism are TEMPORARY, so you wouldn’t want to remove the gland, either surgically or with RAI.

Health problems can be associated with either getting too much iodine OR too little, but are not very straightforward. Goiter, for example, can be caused by either too much or too little iodine. Too little iodine can cause people to be hypothyroid (in the sense that they cannot possibly manufacture sufficient thyroid hormone to maintain healthy metabolism levels). But too much iodine can also cause some people to become hypothyroid. If you can find (at a bookstore or your library) a book called YOUR THYROID, A HOME REFERENCE by Ridgway, Cooper andWood, there is a chapter about iodine that explains some of this in layman’s terms (it starts on page 181). The main gist of this chapter is that we NEED some iodine in our diets, because getting too little would be bad for us, just as getting too much. Graves’ patients are apparently more sensitive than healthy people to extremely high intake of iodine, which is one of the reasons why we are told to avoid kelp tablets, etc. But normal intake of iodine sources should not necessarily cause a problem.

Hope this helps,

Bobbi — Bobbi1536@AOL.com

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