Iatrogenic thyrotoxicosis. Causal circumstances, pathophysiology and principles of treatment. Review of the literature.

Thyrotoxicosis is the clinical syndrome that results when tissues are exposed to high levels of circulating thyroid hormones. In most instances, thyrotoxicosis is due to hyperthyroidism, a term reserved for disorders characterized by overproduction of thyroid hormones by the thyroid gland. Nevertheless, thyrotoxicosis may also result from a variety of conditions other than thyroid hyperfunction. The present report focuses on the etiologies, pathophysiology and treatment of iatrogenic thyrotoxicosis. Iatrogenic thyrotoxicosis may be caused by 1) subacute thyroiditis (a result of lymphocytic infiltration, cellular injury, trauma or radiation) with release of preformed hormones into circulation, 2) excessive ingestion of thyroid hormones ("thyrotoxicosis factitia"), 3) iodine-induced hyperthyroidism (radiological contrast agents, topical antiseptics or other medications). Among these causes of iatrogenic thyrotoxicosis, that induced by the iodine overload and cytotoxicity associated with amiodarone represents a significant challenge. Successful management of amiodarone-induced thyrotoxicosis requires close cooperation between endocrinologists and endocrine surgeons. Surgical treatment may have a leading yet often underestimated role in view of the potential life-threatening severity of this disease, whereas others kinds of iatrogenic thyrotoxicosis are usually treated conservatively.