This document discusses hyperthyroidism, which occurs when the thyroid gland produces excess thyroid hormones. The most common cause is Graves' disease, which is an autoimmune disorder. Symptoms include nervousness, heat intolerance, rapid pulse, and weight loss. Diagnosis involves thyroid function tests, ultrasound, and radioactive iodine uptake scan. Treatment options include antithyroid medications, radioactive iodine therapy, and surgery to remove part or all of the thyroid gland. Complications can include myxedema if the condition is not treated or becomes over-treated.