Control of efficiency and results, and adverse effects of excess iodine administration on thyroid function

The control of the efficiency and the results of iodisation programs can be done clinically, biochemically and by monitoring the side-effects. Clinical improvement (disappearance of all the manifestations of iodine deficiency disease) is the most important end-point. However, some manifestations may persist for life, and so clinical improvement may require a long time interval before becoming apparent. For this reason, biochemical control, especially the urinary iodine excretion, is the most important early sign of the success (or not) of the iodisation programs. Side-effects of iodine in general include: 1. Iodine-induced hyperthyroidism. An increase in toxic nodular goitre is probably transient and eventually its incidence is expected to decrease. However, an increased incidence of autoimmune Graves' disease is probably permanent. 2. Iodine-induced hypothyroidism. 3. Iodine-induced autoimmunity, both of the Hashimoto and of the Graves types. 4. An increase in the incidence of papillary cancers, probably with a decrease in the more aggressive types. In any case, the benefits of iodisation programs far outweigh the risks, provided they are implemented and monitored carefully.