Idiopathic inflammatory myopathies (IIMs), referred to collectively as myositis, are a rare and heterogeneous group of autoimmune diseases characterized by acute, subacute, or chronic muscle weakness.

For information on the clinical presentation of IIMs and diagnostic evaluation, including autoantibody testing, refer to the ARUP Consult Inflammatory Myopathies topic

What’s New

The ARUP Consult Inflammatory Myopathies topic has been updated to include a comprehensive table that indicates which components are included in each of ARUP’s myositis antibody panels, along with the methodology for each component.

ARUP Laboratories Test Panels

The presence of specific autoantibodies is a hallmark in the diagnosis of certain clinical subsets of IIM. Most of these autoantibodies target intracellular proteins, including nuclear and cytoplasmic antigens. ARUP Laboratories offers the following panel tests to assist in the diagnosis of IIM and several subtypes:

  • Extended Myositis Panel 3001781
  • Dermatomyositis and Polymyositis Panel 3001783
  • Polymyositis Panel 2013990
  • Dermatomyositis Autoantibody Panel 3001782
  • Interstitial Lung Disease Autoantibody Panel 3001784

For a comprehensive list of which components are included in which panels, refer to the Myositis Antibody Panels table.

Frequently Asked Questions

Do corticosteroids or medications affect the characteristics of myositis antibodies?

Some autoantibodies may be affected by immunosuppressive treatment. For example, early and/or aggressive immunosuppressant therapies are associated with a decline in SRP and HMGCR antibody levels.

Is there a cure for any form of myositis?

There is no cure for any form of idiopathic inflammatory myopathy (ie, myositis). However, some patients are able to achieve remission (no active disease).

What are the treatment options for myositis?

Treatment depends on the underlying cause. If the condition is caused by viral infection, it does not usually require treatment. If it is caused by bacterial infection, antibiotics are given.

Medication options include:

  • Corticosteroids (eg, prednisone): initially given in high doses and then tapered down
  • Immunosuppressants (eg, methotrexate, azathioprine): given if the condition has autoimmune causes
  • Antibiotics (eg, cefazolin, cephalexin): given if the condition is due to bacterial infection