[Effects of chronic administration of high doses of potassium iodide on iodine metabolism in the rat thyroid gland].

The effect of various doses of KI on iodine methabolism in rat thyroid gland was investigated. Treatment with 1, 3, 10, 100 and 500 physiological daily doses of KI for 14 days had no influence on blood level of thyroid hormones. However, increased administration of KI was accompanied by the increase of iodine in the thyroid gland tissue by 60-121% due to 35-108% and 94-128% increases of protein-bound and free fractions respectively. Chronic treatment with both low and high doses of KI was accompanied by oxidative stress. It is suggested that reactive oxygen species and highly iodinated proteins (particularly thyroglobulin) induced by chronic ingestion of high doses of KI can play the important role in the development of thyroid dysfunctions and autoimmune diseases.