RESUMO
Wolff-Chaikoff effect (WCE) is an acute physiologic response of the thyroid gland to high levels of iodine. The WCE is usually temporary, and the thyroid gland adjusts to high iodine levels within days or weeks. It is a protective mechanism and a failure to escape from it can result in thyroid dysfunction. Hypothyroidism is rare but more likely in patients who have had thyroid disease, are under stress, or are exposed to high iodine concentrations for a long time. The use of iodinated contrast media in radiologic studies or invasive medical procedures is a common source of excessive iodine exposure and can lead to thyroid disfunction. Despite the frequent use of contrast media in health care, the thyroid dysfunction associated with their use is poorly recognized. We report a patient who developed iodine-induced hypothyroidism after chemoembolization of recurrent chylothorax with ethiodized oil (Lipiodol®, Villepinte, France). This case report raises awareness of the importance of the physiologic WCE as well as the relevance of monitoring thyroid function when using iodinated contrast media in patients with specific risk factors.