REPLY
Amiodarone and Thyroid Function
Kishore J. Harjai, MD, and
Angelo A. Licata, MD, PhD
15 October 1997 | Volume 127 Issue 5 Part 1 | Page 653
IN RESPONSE:
Dr. Biddle raises an appropriate question about the use of replacement therapy with triiodothyronine or triiodothyronine and thyroxine (rather than thyroxine alone) in patients with amiodarone-induced hypothyroidism, given that amiodarone inhibits peripheral deiodination of thyroxine to triiodothyronine. We know of no clinical studies that have used triiodothyronine or triiodothyronine and thyroxine in patients with amiodarone-induced hypothyroidism.
We do wish to point out that serum total and free triiodothyronine concentrations are within the normal range in about half of all patients, and serum thyroxine (total and free) concentrations are usually decreased in patients with amiodarone-induced hypothyroidism [1]. Hence, this situation is somewhat different from the cases for which Biddle has reported good results with triiodothyronine or triiodothyronine and thyroxine, cases that are characterized by "normal free thyroxine levels, and low free triiodothyronine levels ... ." Nonetheless, in patients with amiodarone-induced hypothyroidism and low serum levels of thyroxine and triiodothyronine, the potential advantages of combined triiodothyronine and thyroxine preparations need further exploration.
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Author and Article Information
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Ochsner Medical Institutions; New Orleans, LA 70121
Cleveland Clinic Foundation; Cleveland, OH 44195
1. Martino E, Aghini-Lombardi F, Mariotti S, Bartalena L, Lenziardi M, Ceccarelli C, et al. Amiodarone iodine-induced hypothyroidism: risk factors and follow-up in 28 cases. Clin Endocrinol (Oxf). 1987; 26:227-37.
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