Contraindications : Radioactive Iodine

The risk of causing neoplastic changes in the thyroid gland has been constantly under consideration since radioactive iodine was first introduced, and only small numbers of children have been treated in this way. Indeed, many clinics have declined to treat younger patients for fear of causing cancer and have reserved radioactive iodine for patients over some arbitrary age, such as 25 or 30 years. Since experience with ¹³¹I is now vast, these age limits are lower than they were in the past. There is no evidence that radioactive iodine therapy for Graves' disease has caused thyroid or any other form of cancer in adults, although the very large doses that are used to treat cancer may be associated with an increased incidence of leukemia. The use of radioactive iodine during pregnancy is contraindicated; after the first trimester the fetal thyroid would concentrate the isotope and thus suffer damage, but even during the first trimester radioactive iodine is best avoided because there may be adverse effects of radiation on fetal tissues.

Category: Pharmacology Notes