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October 1987

Serum Sex Hormone—Binding Globulin in Amiodarone-Treated Patients: A Marker for Tissue Thyrotoxicosis

Author Affiliations

From the Department of Medicine, University of Massachusetts Medical Center, Worcester (Drs Bambini, Braverman, and Safran); Endocrinologia e Medicina Costituzionale, University of Pisa (Italy) (Drs Aghini-Lombardi, Martino, and Pinchera); Department of Medicine, Columbia University College of Physicians and Surgeons and St Lukes—Roosevelt Hospital Center, New York (Drs Rosner and Khan); and Endocrinologia, University of Cagliari (Italy) (Dr Martino).

Arch Intern Med. 1987;147(10):1781-1785. doi:10.1001/archinte.1987.00370100095016

• The iodinated antiarrhythmic drug amiodarone frequently causes an elevation of the serum thyroxine (T4) level in patients who remain clinically euthyroid. Less frequently, true iodine-induced hyperthyroidism may occur. The clinical and laboratory distinction between these two conditions is often difficult. Since the serum sex hormone—binding globulin (SHBG) concentration is elevated in hyperthyroidism, this study was carried out to evaluate the serum SHBG concentration as a possible marker of hyperthyroidism in patients receiving amiodarone. Patients treated with amiodarone were divided into three groups: clinically euthyroid with normal serum T4 and triiodothyronine (T3) concentrations, clinically euthyroid with elevated serum T4 and normal T3 concentrations, and clinically hyperthyroid with elevated serum T4 and T3 concentrations. The mean serum SHBG concentration was significantly elevated in amiodarone-induced hyperthyroid patients, while it was normal in euthyroid patients treated with amiodarone who had normal or elevated serum T4 concentrations. The results suggest that the hyperthyroxinemia induced by amiodarone is not associated with excess thyroid hormone action in the liver unless the serum T3 concentration is also elevated.

(Arch Intern Med 1987;147:1781-1785)

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