“Is contrast dye bad for the thyroid?”

Since contrast dye can affect highly functioning body organ, thyroid may be a fair game. But i have never made the association

No.

Iodine-containing contrast medium (ICCM), sometimes called contrast or contrast medium, is a chemical substance used in medical X-ray imaging. When injected into the body, ICCM shows what is happening inside the hollow parts of the body (like blood vessels, the stomach, bowel or even the fluid around the spinal cord) on X-ray images or pictures. When injected into a blood vessel, which can be either an artery or a vein, it not only shows the inside of the blood vessel, but it can give information about how the organs supplied by that blood vessel are working. Good examples of this are the kidneys, brain and lungs.

It is important to note that ICCM does not produce radiation: it is a chemical substance that harmlessly interacts with X-rays.

Studies have shown a low percentage of people have long-lasting low thyroid levels after iodine exposure from IV contrast dye for CT scan. Some studies demonstrated some people whose thyroid glands become temporarily & in rare cases permanently hyperactive after exposure to iodine. But in general, the exact risk of thyroid problems after intravenous contrast dye is unknown.

It is not bad for the thyroid. However, iodinated contrast can interfere with evaluation of thyroid disease. Nuclear thyroid scans should not be performed within one month of receiving contrast.

Many, if not most contrast material has iodide, which may affect some blood tests, but it is very unlikely that there will be any effect on the thyroid, but some people have a general allergy, which doctors can easily deal with.