Wolf Chaikoff effect-

Wolff-Chaikoff effect is a phenomenon in which excess iodide transiently inhibits thyroid iodide organification by thyroid peroxidase enzyme thus inhibiting thyroid hormone production leadung to hypothyroidism. In individuals with a normal thyroid, the gland escapes from this inhibitory effect and iodide organification resumes; the suppressive action of high iodide may persist, however, in patients with underlying autoimmune thyroid disease. Reference : page 2285 Harrison's Principles of Internal Medicine 19th edition