Thyrotoxic Myopathy

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What is thyrotoxic myopathy?

Thyrotoxic myopathy is a neuromuscular disorder that may accompany hyperthyroidism (Graves' disease, caused by overproduction of the thyroid hormone thyroxine). Symptoms may include:

  • muscle weakness
  • myalgias (muscle tenderness)
  • wasting of the pelvic girdle and shoulder muscles
  • fatigue
  • heat intolerance

Thyroid myopathy may be associated with rhabdomyolysis (acute muscle breakdown), damage to the muscles that control eye movement, and temporary, but severe, attacks of muscle weakness that are associated with low blood potassium levels (known as periodic paralysis).

Treatment involves restoring normal levels of thyroid hormone and may include thyroid drugs, radioactive iodine, and sometimes partial or complete surgical removal of the thyroid. With treatment, muscle weakness may improve or be reversed.


Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or a loved one improve care for someone with thyrotoxic myopathy?

Consider participating in a clinical trial so clinicians and scientists can learn more about thyrotoxic myopathy and related disorders.  Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with thyrotoxic myopathy at


Where can I find more information about thyrotoxic myopathy?

Information may be available from the following resources:

Child Neurology Foundation


    Order publications from the NINDS Catalog
    The NINDS Publication Catalog offers printed materials on neurological disorders for patients, health professionals, and the general public. All materials are free of charge, and a downloadable PDF version is also available for most publications.