Hyperthyroidism is defined as elevated thyroid levels which is most commonly caused by a thyroid gland which is overactive.  Elevated thyroid levels can also be caused by damage to the thyroid gland from infection or medications which then releases stored thyroid hormone into the blood stream.  When the thyroid is overactive, it is most commonly caused either by thyroid nodules which over-produce thyroid hormone or by Graves’ disease, an autoimmune disease of the thyroid which attacks the thyroid gland and the eyes.  Common symptoms of hyperthyroidism are anxiety, panic attacks, palpitations, weight loss, fatigue, diarrhea and heat intolerance.  Most forms of hyperthyroidism can be treated with medications, surgery or radioactive iodine.