Definition - a disease in which underproduction of thyroxine, which is normally produced by the thyroid gland, causes muscle damage

Cause - often an autoimmune disease, a mistaken attack by the immune system, in this case on the thyroid gland

Onset - childhood to adulthood

Symptoms - weakness around hips and sometimes shoulders; slowing of reflexes; possible muscle stiffness and cramps; can cause muscle enlargement along with weakness; can cause rhabdomyolysis, a severe breakdown of muscle tissue

Progression - can usually be almost completely alleviated by restoring normal thyroxine levels through medication

Inheritance - There appears to be a genetic predisposition to autoimmune diseases.

Facts About Myopathies