Thyrotoxic graves' disease-induced by interferon-ribavirin therapy in a patient with amiodarone-induced hypothyroidism on thyroxine replacement

Abstract

An unusual type of drug-induced thyroid dysfunction is described. Thyrotoxicosis was seen in association with the use of interferon therapy despite prior established amiodarone-induced hypothyroidism. A 63-year-old female patient with a history of hypertension, high-grade ventricular arrhythmia on sotalol 80 mg daily was diagnosed to have amiodarone-induced hypothyroidism previously. She has been receiving thyroxine replacement therapy for 4 years. During the second cycle of interferon for hepatitis C virus relapse. She developed autonomous thyrotoxicosis. Her anti-thyroid peroxidase antibody was persistently negative before, during, and after either amiodarone or interferon while anti-thyroid stimulating hormone receptor antibody titer. Thyroid Tc-99m scan showed a high uptake during interferon therapy. To the best of the author's knowledge, this is the first report of a case of long-term hypothyroidism-induced by amiodarone therapy evolving into thyrotoxic Graves' disease-induced by interferon/ribavirin combination therapy in Libya reflecting an interaction of drugs and the background autoimmune disease.