Wolff-Chaikoff Effect: Iodine induced hypothyroidism. Can occur in normal or hyperthyroid state. Can be used as treatment against hyperthyroidism (i.e thyroid storm); Excess iodide transiently inhibits thyroid iodide organification. In individuals with normal thyroid function, they will undergo the escape phenomena (the gland escapes from this inhibitory effect and iodide organification resumes) after several days.
Jod-Basedow Phenomenon: Iodine induced hyperthyroidism. In individuals with iodine deficient hypothyroidism, thyroid hormone synthesis becomes excessive as a result of increased iodine exposure. NOTE: this does not occur in euthyroid individuals!
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El-Shirbiny AM, Stavrou SS, Dnistrian A, Sonenberg M, Larson SM, Divgi CR. Jod-Basedow syndrome following oral iodine and radioiodinated-antibody administration. 1997 Nov. J. Nucl. Med. 38 (11): 1816–7.
Eng P, Cardona G, Fang S, Previti M, Alex S, Carrasco N, Chin W, Braverman L. Escape from the acute Wolff-Chaikoff effect is associated with a decrease in thyroid sodium/iodide symporter messenger ribonucleic acid and protein. Endocrinology. 1999 Aug;140(8):3404-10.