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Iodine in the treatment of hyperthyroidism

Author
Douglas S Ross, MD
Section Editor
David S Cooper, MD
Deputy Editor
Jean E Mulder, MD

INTRODUCTION

Iodine solutions, such as saturated potassium iodide solutions (SSKI) or potassium iodide-iodine (Lugol's solution), replaced burnt sponge extract in the 19th century as treatment for endemic goiter. By extension, they were sometimes used to treat Graves' disease, but by the end of the century, they were considered to be a dangerous form of therapy. They returned to favor in the 1920s as preoperative treatment for hyperthyroidism and were used in the 1930s as the sole therapy for mild hyperthyroidism prior to the introduction of the thionamides. Today, iodine continues to have a minor role in the treatment of hyperthyroidism.

The role of iodine in the treatment of hyperthyroidism will be reviewed here. The treatment of hyperthyroidism in general is reviewed in detail elsewhere. (See "Graves' hyperthyroidism in nonpregnant adults: Overview of treatment" and "Beta blockers in the treatment of hyperthyroidism" and "Thionamides in the treatment of Graves' disease" and "Radioiodine in the treatment of hyperthyroidism".)

MECHANISM OF ACTION

Iodine has several effects on thyroid function. (See "Iodine-induced thyroid dysfunction" and "Thyroid hormone synthesis and physiology".)

In hyperthyroid patients, iodine acutely inhibits hormonal secretion [1], but the responsible mechanisms are uncertain. This is the most acute effect of iodine on thyroid status, occurring within hours of the start of therapy.

A second effect involves inhibition of iodine organification in the thyroid gland, thereby diminishing thyroid hormone biosynthesis, a phenomenon called the Wolff-Chaikoff effect [2]. Patients with Graves' hyperthyroidism are more sensitive to the inhibitory effect of pharmacologic doses of iodine than normal individuals. Thus, iodine is effective in some patients with Graves' disease because it:

           
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Literature review current through: Oct 2017. | This topic last updated: Jan 30, 2017.
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References
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