Short term administration of potassium perchlorate restores euthyroidism in amiodarone iodine-induced hypothyroidism.

We studied the effect of potassium perchlorate (KClO4) in patients with hypothyroidism due to amiodarone. The short term administration of KClO4 to six such patients led to prompt restoration of euthyroidism, while the three untreated patients remained hypothyroid for 2-6 months. Since KClO4 inhibits thyroid iodide transport, thereby blocking further entrance of iodide into the thyroid and decreasing intrathyroidal iodide content, amiodarone-associated hypothyroidism is probably secondary to the inhibitory effect of excess intrathyroidal iodine on thyroid hormone synthesis.