Diagnosis of myasthenia gravis begins with a medical history and physical exam. The healthcare provider may ask the person to perform repetitive movements of a muscle. The provider looks for signs of muscle weakness with use. A blood test known as antibody titer can often detect the antibodies that attack the muscles
A Tensilon test can be done to diagnose myasthenia gravis. A medicine called Tensilon is given to the person intravenously, or into a vein. If the person has myasthenia gravis, the Tensilon will temporarily strengthen the person's muscles.
Electromyography, or EMG, can be done to measure the way the muscles respond to electrical stimulation. When myasthenia is present, the muscles have an abnormal response to the stimulation.