Surgery is generally an effective treatment for hyperthyroidism but may have disadvantages in some cats. Many cats with hyperthyroidism have heart problems and are higher anesthetic risks. This complication can be life threatening and can result in extra hospitalization and cost. After surgery some cats will develop hypothyroidism and will require treatment with thyroid hormone pills for a period of time. Finally, there is a small risk that the hyperthyroidism will not be cured with surgery, or the condition will reoccur.
Radioactive therapy has some distinct advantages over use of medical or surgical treatment.
Iodine is an element required for normal health. The major effect of thyroid hormone is regulation of metabolic rate. Although essential for life, excess thyroid hormone is toxic to many organs, including the heart and liver. Untreated hyperthyroidism may lead to death. When injected into the body, a large percentage of the radioiodine accumulates in the thyroid gland.