Hyperthyroidism is due to hyperactivity of thyroid gland resulting in the overproduction and release of thyroid hormones.Some times whole gland becomes hyperactive to cause symptoms,in such cases tablets are usually prescribed to control overproduction and once it is controlled surgical removal of gland is done.Radioactive iodine therapy is another option in such cases which causes destruction of gland.Ideally it is also given once hyperactivity is controlled by tablets.RAI is preferred in elderly females who have completed their family,as pregnancy is a contraindication to RAI.Sometimes only part of gland (toxic nodule)becomes hyperactive,such cases are better treated with surgical removal than RAI