Iodine in the treatment of hyperthyroidism
- Douglas S Ross, MD
Douglas S Ross, MD
- Section Editor — Thyroid Disease
- Professor of Medicine
- Harvard Medical School
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
In hyperthyroid patients, iodine acutely inhibits hormonal secretion , 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 . 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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- Ross DS, Burch HB, Cooper DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid 2016; 26:1343.
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- Huang SM, Liao WT, Lin CF, et al. Effectiveness and Mechanism of Preoperative Lugol Solution for Reducing Thyroid Blood Flow in Patients with Euthyroid Graves' Disease. World J Surg 2016; 40:505.
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- Sato S, Noh JY, Sato S, et al. Comparison of efficacy and adverse effects between methimazole 15 mg+inorganic iodine 38 mg/day and methimazole 30 mg/day as initial therapy for Graves' disease patients with moderate to severe hyperthyroidism. Thyroid 2015; 25:43.
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- Institute for Safe Medication Practices; Medication Safety Alert December 1, 2011. Look Out of Lugol's...Error-Prevention Strategies for this Strong Iodine Solution https://www.ismp.org/newsletters/acutecare/showarticle.aspx?id=10 (Accessed on January 13, 2017).
- Kinoshita H, Yasuda M, Furumoto Y, et al. Severe duodenal hemorrhage induced by Lugol's solution administered for thyroid crisis treatment. Intern Med 2010; 49:759.
- Park JM, Seok Lee I, Young Kang J, et al. Acute esophageal and gastric injury: complication of Lugol's solution. Scand J Gastroenterol 2007; 42:135.
- MECHANISM OF ACTION
- Graves' disease
- - Preoperative preparation
- - Adjunctive therapy after radioiodine or with thionamides
- - Is there a role for long-term iodine therapy?
- Thyroid storm
- IODINE PREPARATIONS AND DOSING
- ADVERSE EFFECTS
- SOCIETY GUIDELINE LINKS
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS