Having an overactive thyroid, which produces and releases more thyroid hormone than your body needs, is also known as hyperthyroidism. Women are 5 to 10 times more likely to develop hyperthyroidism than men. The most common cause of hyperthyroidism is an autoimmune condition called Graves' disease. With this disease, the body's immune system creates an antibody that causes the gland to make an excessive amount of thyroid hormone. Other causes of hyperthyroidism are nodules on the thyroid or an inflammation of the thyroid, called thyroiditis.
Your doctor can screen for hyperthyroidism with blood tests for Thyroid-Stimulating Hormone (TSH), elevated thyroid hormone levels, or a thyroid-stimulating antibody indicative of Graves' disease. An overactive thyroid is typically treated with anti-thyroid drugs, radioactive iodine, or surgery.