What Causes Hyperthyroidism?

There are several different causes of hyperthyroidism:

  • The entire thyroid gland may be overactive, producing too much hormone. Doctors call this problem diffuse toxic goiter, or Graves’ disease.
  • One or more lumps (also called nodules) in the gland may be overactive. One such lump is called a toxic autonomously functioning thyroid nodule, and several lumps are called a toxic multi-nodular goiter.
  • The gland may be inflamed, a condition called thyroiditis. It can release the thyroid hormone that was stored in the gland, causing hyperthyroidism that lasts for a few weeks or months.
  • Some patients may take more thyroid hormone pills than needed or prescribed.
  • Some drugs, such as Quadrinal®, amiodarone (Cordarone®), and Lugol’s solution, contain large amounts of iodine, a chemical the thyroid uses to produce its hormones, and may cause the thyroid to produce too much hormone.

® Quadrinal is a registered trademark of Knoll Pharmaceutical.
® Cordarone is a registered trademark of Wyeth Labs.