The prevention and management of iodine-induced hyperthyroidism and its cardiac features

Review of available literature and experience supports a recommended daily iodine intake of 150 mu g for adults, 200 mu g during pregnancy, 50 mu g for the first year of life, 90 mu g for ages 1 to 6, and 120 mu g for ages 7 to 12. The amount of iodine added to salt in fortification programs should be adjusted to achieve these intakes. Iodine-induced hyperthyroidism (IIH) is an occasional consequence of the correction of iodine deficiency, occurring most frequently in older subjects with multinodular goiter. This complication is usually mild and self-limited, but may be serious and occasionally lethal. The most important clinical manifestations are cardiovascular. Thyrotoxicosis can aggravate pre-existing cardiac disease and can also lead to atrial fibrillation, congestive heart failure, worsening of angina, thromboembolism, and rarely, death. In the absence of pre-existing cardiac disease, treatment of thyrotoxicosis usually returns cardiac function to normal. Heightened awareness on the part of the health sector will promote early detection and prompt treatment of IIH. Monitoring should be an important part of a successful program of iodization, and in addition it offers the best opportunity for recognizing and treating IIH. Further research to improve the characterization and prevention of IIH is strongly encouraged. The most important conclusion is that IIH, while an issue that needs serious address, is not a reason to stop iodine supplementation in deficient regions. The benefits to the community from correcting iodine deficiency and avoiding its associated disorders far outweigh the damage from IIH.