Myasthenia Gravis Tests
Reviewed
Myasthenia gravis (MG) tests help diagnose a chronic autoimmune disease that causes muscle weakness. Your immune system makes antibodies that block or change the connection between your nerves and muscles. Testing can involve multiple procedures, including a blood antibody test, neurological exam, ice pack test, electromyography (EMG), nerve conduction study, imaging, edrophonium test, and lung function tests. There is no cure, but treatments can relieve symptoms and may allow periods without symptoms (remission).
Preparation and collection
No special preparation is needed for a neurological exam, ice pack test, or antibody test. For other tests, you may need to fast or avoid certain foods and beverages. Tell your provider if you are pregnant, have metal in your body, have a pacemaker or cardiac defibrillator, or take any medicines (especially blood thinners).
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- MG can be hard to diagnose because muscle weakness can be a symptom of many disorders. Your provider may order more than one type of test.
- A negative antibody test does not rule out MG.
- The edrophonium test may cause an allergic reaction (rare); contact your provider if you have breathing problems, vision changes, or feel faint.
- EMG may cause slight pain or cramping; if pain becomes very uncomfortable, let your provider know as it may change test results.
- Nerve conduction study may cause a mild tingling feeling; tested muscles may be sore for a few days.
What to do next
If diagnosed with MG, your provider will work with you on a treatment plan. Lifestyle changes that may help include eating a healthy diet, doing regular gentle exercise (check with your provider first), avoiding heat and stress, wearing an eye patch for double vision, and taking naps or rest breaks.