What Causes Hyperthyroidism?

  • An autoimmune disorder, such as Graves’ disease (this is the most common cause of hyperthyroidism)
  • One or more thyroid nodules (growth/s within the thyroid gland) that make excess thyroid hormone
  • Inflammation of the thyroid gland, such as thyroiditis
  • Over-treatment of an underactive thyroid (if too much thyroid hormone is taken for replacement)
  • Genetic conditions and rare ovarian tumors
  • A tumor in the pituitary gland (a small gland in the brain that controls other glands in the body) that make an excess of a hormone called thyroid stimulating hormone (TSH) that pushes the thyroid gland to make too much thyroid hormone

Thyroid storm is a rare, but very serious type of hyperthyroidism in which thyroid hormone levels are extremely high.

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Rev. 11/2019. MassGeneral Hospital for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.