A Case Report on Type 2 Amiodarone Induced Thyrotoxicosis and Hypercalcemia

Amiodarone, the most commonly used antiarrhythmic drug, can cause either hypothyroidism by inhibiting iodide transport into the thyroid gland or hyperthyroidism. We present a rare case of type 2 amiodarone-induced thyrotoxicosis with hypercalcemia. A 64-year-old man with systolic heart failure, hypertension, and hyperthyroidism presented with complaints of dyspnea on exertion, orthopnea, and vomiting for several days. Laboratory tests showed low thyroid stimulating hormone <0.01 mIU/L, high free triiodothyronine (FT3) of 24.8 ng/dL, free thyroxine (FT4) of >5.0 ng/dL, and hypercalcemia of 12.9 mg/dL. Hypercalcemia, a rare presentation of AIT, was treated with calcitonin and intravenous fluids. The patient was taken off methimazole and started on propylthiouracil for the persistent elevation of thyroid hormones, especially FT3, and to reduce the conversion of T4 to T3. The patient was not completely responding to treatment with propylthiouracil alone, so prednisone was added to the regimen on day 12, effectively returning the patient to the euthyroid state.