Hyperthyroidism is commonly caused by Graves' disease, which is an autoimmune disorder. Graves' disease accounts for 60-80% of hyperthyroidism cases. It is caused by antibodies that stimulate the thyroid gland and cause excessive production of thyroid hormones. Common symptoms include weight loss, rapid heartbeat, nervousness, and eye changes. The eyes may become protruded (proptosis), inflamed, and cause double vision (diplopia). Laboratory tests show suppressed TSH and elevated thyroid hormone levels. Graves' disease is treated by controlling thyroid hormone levels, managing eye symptoms, and in severe cases using medications, radiation therapy, or surgery.