Iodide contrast used to sharpen some diagnostic images seem to have an unrecognized dark side. A study published in the Archives of Internal Medicine was based on 20-year follow-up data of nearly 2,000 people who had undergone CT scans, cardiac catheterization or angiograms. People who later developed thyroid disease, with their thyroid glands becoming overactive or underactive, were two to three times more likely than other patients to have received iodide-containing contrast material. Although this type of reaction has been previously reported from Europe, this study is the largest as well as the most recent in the U.S. to document the link between iodide exposure and thyroid dysfunction.
The authors warn that their findings should not keep people from getting needed diagnostic work-ups. An accompanying editorial urges doctors to keep the patient’s broad health picture in mind when ordering tests. Those who may be especially susceptible to thyroid problems should be monitored closely for some time after an unavoidable iodide exposure. Patients who have such tests should be alert for symptoms of over or underactive thyroid function.
[Archives of Internal Medicine, January 23, 2012]

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  1. cpmt

    I had skin problems since I was given a few years ago (4) my face and arms get very red (and scale flakes in the face like eczema). No one say anything (doctors about my complain, they don’t’ tell you the side effects) but it really bather me. Some people are very allergic to Iodine/dye etc.. from CAT and MRI’s and doctors don’t advise or tell you before you have that done.

    • Tammy

      Hi there! I had a ct scan 3 days ago and since the. My face, neck and chest have been red and hot to the touch. Does this sound like what happens to you? What have you used to help it?

  2. Elize O

    I had two CT’s done with iodine.(Chest 2007) and (abdomin Jan.2013) Have suffer from most of the symptoms of hyperactive thyroid. The weight loss of 16Kg over a period of 8 months, leaving me at 38Kg is a real concern. I am 73 years of age.
    A thyroid lab result on 11/06/13 showed the levels within the normal range, but T4 (15.5) at the high end of normal and TSH (0.81) at the low end of normal. A more recent test showed T4-13.7 and TSH-1.06 which is an improvement.
    My questions: 1. Are there any steps I can take to normalise the levels, like e.g. avoid iodine altogether or supplement with it?
    2. Could lab tests be done for iodine levels?
    I would rather follow the preventative route and avoid RAI if possible!
    Would greatly appreciate some advice.
    Kind regards
    Elize O

  3. Elize O

    I had Ct-scans with iodine during 2007 and January 2013.
    Recent thyroid test results: 11/06/2013: T4-15.5 TSH-0.81
    29/07/2013: T4-13.7 TSH-1.06
    Although the levels are within the “normal” range and a slight improvement, I have most of the very unpleasant symptoms. The weight loss of 16Kg over a period of 8 months is a serious concern. Now 38Kg. My physician does not think I should see an endocrinologist yet.
    My questions: 1. What do I do, avoid iodine altogether or supplement with it? I would rather if possible, try to avoid the RAI option!
    2. Can iodine levels be tested by the lab?
    Hoping that you can help me!
    Kind regards
    Elize O

  4. PV

    My partner has had excess iodine exposure from unmonitored Amiodarone for 3 years and a recent angiogram. He has lost 12 kilos in a couple of weeks and is very unwell. The doctors are not saying much. What can they do for him?

  5. Ruth K.

    I had a pipida gall bladder scan and a few months later I had a yearly exam and showed positive for hyperthyroid. I have wondered if the dye that I was injected with could have had a negative effect on my thyroid. Has this happened to anyone else?
    PEOPLE’S PHARMACY RESPONSE: It has been documented as a possible side effect of iodine-containing contrast material.

  6. JT

    This is very interesting. I was diagnosed with Hypothyroidism within a few years of moving to a new state. I thought that maybe it was stress or the water or some other change but never could quite pinpoint it. Just assumed it was me getting older- I was 30-something.
    Ten years later now I check my records because I remember having a CT scan with iodine. Within a couple years of that scan I was diagnosed. And that was only because I waited so long to see a doctor for my fatigue. It may be a guess, but I feel like I have my explanation now.

  7. Dolores

    I don’t understand. If you need iodine for the proper function of the thyroid, why would the iodine in contrast cause problems with the thyroid? That is why iodine was put in table salt to cut down
    on the rise in goiters, etc.
    The dose that people receive when they get “contrast” for their CT scans or angiograms is WAY higher than anything anyone would be exposed to normally: Here is what the researchers say about this:
    A typical dose of ICM [Iodinated Contrast Media] contains approximately
    13,500 μg of free iodide and 15
    to 60 g of bound iodine that may be liberated
    as free iodide in the body. This
    represents an acute iodide load of 90 to several
    hundred thousand times the recommended
    daily intake of 150 μg. Sudden
    exposure to high iodide loads, given in
    other contexts, can disrupt thyroid hormone
    regulation, resulting in hypothyroidism
    (Wolff-Chaikoff effect) or hyperthyroidism

  8. CB

    I always thought that table salt was ‘Iodized’ to promote thyroid function. But here you state that Iodine can harm the thyroid. I am confused. Are some forms of Iodine helpful to the thyroid while other forms of Iodine are harmful?
    People’s Pharmacy response: The issue is probably more dose than form, although the form of iodine might also be relevant. Your body needs a little bit of iodine because the gland uses iodine in thyroid hormones. T3=3 atoms of iodine in the hormone. T4=4 atoms of iodine. Converting T4 to T3 requires an enzyme that can remove one iodine atom from the hormone to produce the active form.
    We are not quite sure how excess iodine throws the thyroid gland out of balance, but it does. This is probably what is happening with exposure to iodide contrast media. Please note that by no means everybody, nor even a majority of patients, will have a thyroid problem as a result. But it is a possibility.

  9. acmm

    I noticed this article is titled “iodine-contrast” but “iodide-contrast” is used in the text. Are these the same??
    People’s Pharmacy response: Iodine is the element; iodide refers to the iodine-containing compounds found in the contrast material. It is the iodine that can do the thyroid gland harm.

  10. Penny H.

    The last time I had a CT scan with iodine contrast I broke out in hives. It wasn’t a serious problem but now iodine contrast is now on my list of allergies.
    People’s Pharmacy response: Be sure to let any future physicians who plan to scan know you have had such a reaction. It’s not uncommon.

  11. cpmt

    Yes, the last CAT scan I had done I asked to cover my neck, the nurse looked at me like I was coming from the Moon or… she didn’t covered.

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