[Thyroid disorders associated with external radiation in children and adolescents].

The effects of ionizing radiation on the thyroid have been studied for several decades, and nuclear accidents are the major source of information about the subject. There is an association of hypothyroidism, hyperthyroidism, thyroid nodules and cancer with radiation, but the threshold dose, mechanism of injury, and some risk factors have not been fully established. Children are more susceptible to thyroid injury caused by radiation and require prolonged follow-up after exposure. This issue is especially relevant nowadays, since a large number of people treated with radiation for childhood cancer survive and may have sequelae. Diagnostic radiology tests also represent a source of exposure to radiation in the pediatric population. In this review, we analyze different clinical and pathological changes, and the mechanisms of thyroid lesions caused by radiotherapy and computed tomography in children and adolescents. It is important to understand these data for prevention, early detection, and treatment of thyroid dysfunction.