Due to the many different forms of inflammatory myositis and similarities to other muscular and nerve diseases, it may take a few visits to the doctor before the condition can be diagnosed. After a careful physical examination, the doctor will order other tests to confirm the diagnosis. Such tests may include:
1. Routine tests like a full blood count, Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP).
2. Blood tests for muscle enzymes and auto-antibodies. Muscle enzyme levels (usually raised initially) are useful for monitoring progress and response to treatment.
3. Other Investigations:
• Electromyogram (EMG)This is a test that measures the electrical activity of muscles. In patients with inflammatory myositis the EMG would be abnormal.
• Muscle BiopsyThe doctor takes a sample of the affected muscle to be examined under the microscope. The procedure is done under local anaesthesia.
• X-ray of the chestTo investigate for lung cancer and lung involvement associated with inflammatory myositis.
• Magnetic Resonance Imaging (MRI)This painless scan can identify abnormal muscles and can be used to locate the best site for a biopsy and to monitor the progress of the disorder.
• A chest and abdominal CT scanThis test is useful to investigate for hidden cancers.
• Gastroscopy and colonoscopyThese tests are useful to investigate for underlying cancers in the gastrointestinal tract.