Dear Dr. Roach: I am a male who is 58 years of age. I recently had an MRI of my cervical spine, and just this month, I had a CT scan of my whole abdomen. Since then, I have had symptoms of dry eyes, weight loss and insomnia. I wondered if the contrast dye used for the MRI or CT scan can cause hyperthyroidism, as these are common symptoms for excess thyroid hormone. Do you think I have hyperthyroidism? — G.L.

Answer: You are quite right that all the symptoms are commonly seen in people with excess thyroid. The weight loss is due to the increased metabolism of people with excess thyroid hormone. Insomnia is also common for similar reasons. Palpitations, tremor, anxiety, frequent bowel movements, and heat intolerance are all classical symptoms of excess thyroid hormone.

You are also right that the iodine-containing dye from CT scans can precipitate hyperthyroidism in a person who is destined to get it. However, the risk of this occurring is low. There is no increased risk of thyroid disease with MRI dye.

You could indeed have hyperthyroidism, and if you saw your doctor, you would very likely be tested. (I would certainly do so if I had a patient with these symptoms.) My experience is that these symptoms are not specific to thyroid disease, and it is probably some other cause. So, I would not be surprised if your thyroid tests were normal.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.