Amiodarone and Hypothyroidism

A 65-year-old man attended our outpatient clinic for diagnostic evaluation of abnormal blood tests detected during a routine check requested by his cardiologist. The investigations showed a raised serum gamma-glutamyl transferase (406 U/L; normal <60) and a raised serum thyroid-stimulating hormone (TSH) concentration of 99·20 μIU/mL (normal 0·27–4·20). The patient's free thyroxine and free tri-iodothyronine were low at 0·67 ng/dL (normal 0·93–1·70) and 1·5 pg/mL (normal 2·0–4·4) respectively. Anti-thyroid antibodies—including thyroid peroxidase antibodies and anti-thyroglobulin antibodies—were not detected.