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Hyperthyroidism With a Low Radioactive Iodine Uptake

Hyperthyroidism With a Low Radioactive Iodine Uptake Abstract To the Editor.— In small doses, inorganic iodide can function to inhibit thyroglobulin proteolysis. In larger doses, it can also block iodination of tyrosine residues within the thyroglobulin molecule. In either case, a hypothyroid state can be induced (Wolff-Chaikoff effect), which is usually transient and subject to escape. This escape phenomenon is not universal. Individuals who have abnormal thyroid tissue (autoimmune thyroiditis, or acquired after radioactive iodine therapy) often will remain hypothyroid with inorganic iodide treatment.1 Amiodarone therapy may also result in prolonged hypothyroidism. Iodide administration may therefore cause a persistent decrease in thyroid hormone production.2 More frequently,3 iodide has also been shown to induce thyrotoxicosis (iod-Basedow effect) and cause immunologic aberrancies.Iodide treatment of hyperthyroidism will not achieve euthyroidism in up to 25% of individuals.2 The radioactive iodine uptake in this group will remain low due to a dilutional effect from the exogenous iodide, despite References 1. Ross S, Daniels GH, DeStefano P, Maloof F, Ridgeway EC. Use of adjunctive potassium iodide after radioactive iodine treatment of Graves' hyperthyroidism . J Clin Endocrinol Metab. 1983;57:250-253.Crossref 2. Emerson CM, Anderson AJ, Howard WJ, Utiger RD. Serum thyroxine and triiodothyroxine concentration during iodide treatment of hyperthyroidism . J Clin Endocrinol Metab. 1975;40:33-36.Crossref 3. Solomon BL, Evaul JE, Burman KD, Wartofsky L. Remission rates with antithyroid drug therapy: continuing influence of iodine intake? Ann Intern Med. 1987;107:510-512.Crossref 4. Shetty KR, Duthie EH. Thyrotoxicosis induced by topical iodine application . Arch Intern Med. 1990;150:2400-2401.Crossref 5. Wynn DR, Rodriguez M, O'Fallon WM, Kurland LT. Update on the epidemiology of multiple sclerosis . Mayo Clin Proc. 1989;64:808-817.Crossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Internal Medicine American Medical Association

Hyperthyroidism With a Low Radioactive Iodine Uptake

Archives of Internal Medicine , Volume 151 (11) – Nov 1, 1991

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Publisher
American Medical Association
Copyright
Copyright © 1991 American Medical Association. All Rights Reserved.
ISSN
0003-9926
eISSN
1538-3679
DOI
10.1001/archinte.1991.00400110148037
Publisher site
See Article on Publisher Site

Abstract

Abstract To the Editor.— In small doses, inorganic iodide can function to inhibit thyroglobulin proteolysis. In larger doses, it can also block iodination of tyrosine residues within the thyroglobulin molecule. In either case, a hypothyroid state can be induced (Wolff-Chaikoff effect), which is usually transient and subject to escape. This escape phenomenon is not universal. Individuals who have abnormal thyroid tissue (autoimmune thyroiditis, or acquired after radioactive iodine therapy) often will remain hypothyroid with inorganic iodide treatment.1 Amiodarone therapy may also result in prolonged hypothyroidism. Iodide administration may therefore cause a persistent decrease in thyroid hormone production.2 More frequently,3 iodide has also been shown to induce thyrotoxicosis (iod-Basedow effect) and cause immunologic aberrancies.Iodide treatment of hyperthyroidism will not achieve euthyroidism in up to 25% of individuals.2 The radioactive iodine uptake in this group will remain low due to a dilutional effect from the exogenous iodide, despite References 1. Ross S, Daniels GH, DeStefano P, Maloof F, Ridgeway EC. Use of adjunctive potassium iodide after radioactive iodine treatment of Graves' hyperthyroidism . J Clin Endocrinol Metab. 1983;57:250-253.Crossref 2. Emerson CM, Anderson AJ, Howard WJ, Utiger RD. Serum thyroxine and triiodothyroxine concentration during iodide treatment of hyperthyroidism . J Clin Endocrinol Metab. 1975;40:33-36.Crossref 3. Solomon BL, Evaul JE, Burman KD, Wartofsky L. Remission rates with antithyroid drug therapy: continuing influence of iodine intake? Ann Intern Med. 1987;107:510-512.Crossref 4. Shetty KR, Duthie EH. Thyrotoxicosis induced by topical iodine application . Arch Intern Med. 1990;150:2400-2401.Crossref 5. Wynn DR, Rodriguez M, O'Fallon WM, Kurland LT. Update on the epidemiology of multiple sclerosis . Mayo Clin Proc. 1989;64:808-817.Crossref

Journal

Archives of Internal MedicineAmerican Medical Association

Published: Nov 1, 1991

References