A nurse is educating a 35-year-old client with hyperthyroidism about the use of radioactive iodine-131 for treatment. Which statement made by the client indicates a correct understanding of this treatment?

Rationale: A. Follow-up is essential after radioactive iodine therapy to monitor thyroid hormone levels and detect potential hypothyroidism or residual hyperthyroidism. Patients typically require periodic blood tests for months to years after treatment. B. Radioactive iodine-131 selectively destroys overactive thyroid tissue, which decreases the production of thyroid hormones. This mechanism is why it is effective for treating hyperthyroidism, especially in conditions like Graves’ disease or toxic nodular goiter. C. Radioactive iodine-131 is contraindicated during pregnancy and breastfeeding because it can cross the placenta and damage fetal thyroid tissue, potentially causing congenital hypothyroidism. D. Antithyroid medications, such as methimazole or propylthiouracil, are often first-line therapy, especially in younger clients or those who are pregnant. Radioactive iodine is typically used when medication fails, is not tolerated, or as definitive therapy in adults.