Abstract

Amiodarone causes dynamic changes in thyroid hormone levels in all patients. Approximately 3 months after starting amiodarone a new steady state is achieved where fT4 remains close to the upper limit of the reference range and TSH becomes normalised. Thyroid dysfunction evolves in around 20% of patients. In the case of hypothyroidism, treatment with amiodarone can be continued. Subclinical hypothyroidism can be followed with 4-6 month intervals without treatment. Overt hypothyroidism is treated with L-thyroxin aiming at fT4 in the reference range and TSH close to the upper limit of the reference range. Hyperthyroidism mandates discontinuation of amiodarone. We suggest that all patients with amiodarone- imduced hyperthyroidsm should have prompt referral to the endocrinologist. Type 1 amiodarone-induced hyperthyroidism is caused by excess uncontrolled thyroid hormone synthesis due to iodine excess, which is treated with thyreostatic agents. Type 2 amiodarone-induced hyperthyroidism is caused by destructive thyroiditis and is treated with glucocorticoids.