Myopathy refers to diseases that affect skeletal muscles (muscles that connect to your bones). These diseases attack muscle fibers, making your muscles weak.


  • Having a family history of myopathy. This increases the likelihood you might inherit an abnormal gene that causes muscle disease.

  • Being designated male at birth (DMAB). Some myopathies are carried on the X chromosome, and actually affect more men than women. Other inherited forms of myopathy carried on other chromosomes affect all sexes equally.

  • Having an autoimmune, metabolic or endocrine disorder.

  • Being exposed to certain medications or toxins (see toxic myopathy below for a list of some of these medications).


  • Muscle weakness, most commonly of your upper arms and shoulders and thighs (more common and more severe).

  • Muscle cramps, stiffness and spasms.

  • Fatigue with exertion.

  • Lack of energy.


  • Blood tests - Muscle enzymes such as creatine kinase (CK) or aldolase may be elevated in certain myopathies as a result of the breakdown of muscle fibers.

  • Electrolyte levels such as sodium, magnesium, potassium, calcium and phosphorus.

  • Autoimmune disease testing such as antinuclear antibodies (ANA), rheumatoid factor, sedimentation rate and c-reactive protein.

  • Endocrine testing such as thyroid hormone.

  • Electromyography (EMG and nerve conduction studies), including testing the electrical conduction of your nerves and needle examination of your muscles to assess the type and degree of muscle damage.

  • Magnetic resonance imaging (MRI) of your muscles.

  • Genetic tests.

  • Muscle biopsy, in which your healthcare provider surgically removes a small piece of muscle tissue for testing.


The goal of treatment is to decrease inflammation and your body’s autoimmune response. These myopathies are often treated with:

  • Immunomodulatory/immunosuppressant drugs such as methotrexate, cyclosporine, tacrolimus, azathioprine, mycophenolate, rituximab and intravenous (IVIg) or subcutaneous (SubQIg) immunoglobulin.

  • Corticosteroids such as prednisone or methylprednisolone.

Inherited and genetic myopathies

  • Most inherited and genetic myopathies don’t have a specific treatment or cure.

  • Management is largely based on symptom control and different forms of therapy.

  • There are multiple ongoing clinical trials in various areas of research looking at treatments and gene therapy.

  • Duchenne muscular dystrophy and Pompe disease are disorders that can be treated with specific medication.

Other acquired myopathies

  • Healthcare providers manage acquired myopathies including endocrine, toxic and infectious myopathies by treating the underlying disease causing the myopathy.

  • Toxin-related myopathies are treated by stopping the offending agent (alcohol or toluene, for example) or medication (statins, for example).

  • Muscle symptoms that result from infections caused by bacteria, viruses or other infectious organisms are improved by treating the infection directly with antibiotics.

diseases treatments myopathy health prevention muscular-system disorders

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