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, and/or 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.
The NINDS supports a broad range of research on neuromuscular disorders such as thyrotoxic myopathy. Much of this research is aimed at learning more about these disorders and finding ways to prevent and treat them.
National Institute of Diabetes and Digestive
and Kidney Diseases (NIDDK)
National Institutes of Health, DHHS
31 Center Drive, Rm. 9A06 MSC 2560
Bethesda, MD 20892-2560
Tel: 301-496-3583 TTY: 866-569-1162
Muscular Dystrophy Association
National Office - 222 S. Riverside Plaza
Chicago, IL 60606
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.
All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.
Last Modified October 4, 2011