An epidemic of hyperthyroidism following salt iodination in Lebanon.

Salt iodination, in Lebanon, started partially in late 1992, and was implemented in a uniform manner by January 1995. Following salt iodination, an epidemic of iodine-induced thyrotoxicosis occurred, as noted by the author, in his private clinic. The number of thyrotoxic patients increased sharply by 2 to 6 folds, and the yearly incidence rose from a baseline of 0.02% up to 0.07%. The younger patients have predominantly Graves' disease (32% of the cases), while 17% have solitary thyroid nodules, and 44% of the cases were elderly subjects with multinodular goiter. The pathogenesis and possible causes of this epidemic are discussed.