Hyperthyroidism affects between 1 and 3 percent of people in the United States and is more common in women.
Graves’ disease is the most common cause of hyperthyroidism, affecting about 70 percent of people with an overactive thyroid. Nodules on your thyroid — a condition called toxic nodular goiter or multinodular goiter — can also cause the gland to overproduce its hormones.
Hyperthyroidism can also be caused by:
Excessive thyroid hormone production may lead to symptoms that can include: