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December 1984

Amiodarone-Induced Relative Pituitary Insensitivity

Arch Intern Med. 1984;144(12):2433. doi:10.1001/archinte.1984.00350220169049

To the Editor.  —In the March Archives Amico et al1 speculated that the antiarrhythmic drug amiodarone may affect the sensitivity of peripheral organs, especially the pituitary gland, to the biologic effects of thyroid hormones. Based on the results of ten thyrotropin-releasing hormone (TRH) tests (measurement of thyrotropin (TSH) before and after intravenous injection of TSH-releasing hormone, they suggested an amiodarone-induced insensitivity of the pituitary to circulating serum levels of thyroxine (T4).We would like to substantiate this finding with our data: the Figure shows that levels of high free T4 do not necessarily mean a suppressed TSH-secretion in patients treated with amiodarone. However, a significant negative correlation between free T4 and basal TSH and TRH-stimulated TSH serum concentrations was observed in our euthyroid patients on receiving amiodarone. (Patients were assumed to be euthyroid on the basis of clinical symptoms and on the lack of increased triiodothyronine