Thyroid nodules are growths on your thyroid. They are usually benign (not cancer). They may become overactive and make too much of the thyroid hormone.

All types of hyperthyroidism are due to an overproduction of thyroid hormones. Hyperthyroidism (an overactive thyroid) causes your thyroid to make more thyroid hormone than your body needs. Hyperthyroidism can accelerate your body functions such as your metabolism (can cause unintentional weight loss) or a rapid or irregular heart rate.