Administration or ingestion of excess dietary iodine (exceeding 150 mcg daily) found in processed foods, iodized salt, contrast dyes for imaging tests, salty foods, medications such as amiodarone, dietary supplements including thyroid and metabolic boosters, and contaminated meat can result in thyrotoxicosis especially in patients with multinodular goiter, latent Graves’ disease, and adenomas.

In addition, excessive iodine can trigger Graves’ disease and other autoimmune thyroid disorders in genetically predisposed individuals who have not yet developed a thyroid disorder and cause relapses in individuals who have achieved remission.

Latent Graves' disease is a term used to describe Graves' disease that's in remission from antithyroid drug therapy or alternative medicine. Latent Graves' disease also refers to mild conditions that may not have yet been diagnosed.

Excess iodine can cause hypothyroidism in certain patients. Patients with a history of Graves’ disease treated with radioiodine or partial thyroidectomy, partial thyroidectomy for thyroid nodules, or autoimmune thyroiditis appear to be particularly predisposed to iodine-induced hypothyroidism. Even relatively small excessive doses of 750 mcg may be sufficient to induce hypothyroidism in these individuals.

Source:

Kopp, Peter. 2010. “Thyrotoxicosis of Other Etiologies,” in Thyroid Disease Manager Clinical Textbook available online.  http://www.thyroidmanager.org/chapter/thyrotoxicosis-of-other-etiologies/