[Hyperthyroidism due to the improper use of povidone-iodine]

A 48-year-old female was referred to Perugia Hospital because of cardiac palpitations and insomnia. The clinical history, the physical examination and laboratory tests were supportive of hyperthyroidism. Since July 1994 the patient had been combating constipation by improper use of an iodine-containing antiseptic cream for external use only. She had inserted povidone-iodine into the rectum by means of a cannula. The iodine-containing cream was suspended, and a beta-blocker prescribed. Cardiac palpitations disappeared within 2 weeks, and plasma thyroid hormone levels returned to normal within 1 month. Hyperthyroidism in this patient was probably triggered by improper long-term use of an over-the-counter cream. When investigating the etiology of hyperthyroidism, a history of long-term use of iodine-containing medication should always be considered. These medications should be used with caution for only short periods of time and, if usage is prolonged, medical supervision should be recommended; above all, they should be applied only as directed.