Historical Tidbit: Jan Wolff (b. April 25, 1925) and Israel L. Chaikoff (b. July 2, 1902)—the Wolff-Chaikoff Effect
Submitted by Alan D. Rogol, M.D., Ph.D.
Wolff and Chaikoff discovered that excessive doses of iodine administered acutely to rabbits, transiently inhibited organification of iodine in the precursors of thyroxine. They noted specifically that excessive iodine exerts its inhibitory effect (autoregulation) upon the oxidative reaction leading to the iodination of the phenolic group of tyrosine of the precursor, di-iodotyrosine (DIT) and its coupling to thyroxine (Endocrinology 1948; 43:174). This pharmacologic effect became the basis for iodine administration before thyroidectomy for thyrotoxicosis. It should be noted that escape from this inhibition leads to worsening of the thyrotoxicosis, which reverts to prior observations that excessive iodine in the diet might lead to thyrotoxicosis (iodine-induced thyrotoxicosis or the Jod-Basedow phenomenon).