Diagnosing myositis is often a complicated and lengthy process. Different tests and examinations help doctors establish an accurate diagnosis so you can begin treatment as soon as possible.
During your clinical exam, your doctor will ask questions about your health in general, including detailed personal and family health histories. The doctor will want to know when you first saw signs of the skin rash or muscle weakness, and will examine your muscle strength and any skin symptoms.
The doctor may use one or more of the following tests to help confirm a specific diagnosis:
- Conventional blood tests: Doctors look for elevated levels of muscle enzymes in patients' blood samples.
- Muscle and skin biopsy: Small samples of muscle tissue show abnormalities in muscles, including inflammation, damage, and abnormal proteins. For those with skin symptoms, doctors often biopsy a piece of skin to study.
- Electro-diagnostic tests: Muscle resonance imaging scans (MRI) reveal inflammation in muscles; electromyograms (EMG) detect changes in muscles' electrical patterns that indicate muscle disease and which muscles are affected.
- Antibody testing: Since the discovery of certain myositis-specific and myositis-associated antibodies, more detailed blood testing confirms a diagnosis and provides insight into the possible course of the disease as well as potential complications.
Other tests may rule out another type of disease or condition that has similar symptoms to myositis. Many doctors now routinely screen newly diagnosed patients for cancer or lung disease (see complications). If you have questions about any test, talk with your doctor or lab technician
Updated March 2012