Myasthenia Gravis Blood tests

If the diagnosis is suspected, serology can be performed in a blood test to identify certain antibodies:

1. One test is for antibodies against the acetylcholine receptor. The test has a reasonable sensitivity of 80–96%, but in MG limited to the eye muscles (ocular myasthenia) the sensitivity falls to 50% (negative in up to 50% who have MG).
2. A proportion of the patients without antibodies against the acetylcholine receptor have antibodies against the MuSK protein.
3. In specific situations (decreased reflexes which increase on facilitation, coexisting autonomic features, suspected presence of neoplasm, especially of the lung, presence of increment or facilitation on repetitive EMG (electromyography) testing) testing is performed for Lambert-Eaton syndrome, in which other antibodies (against a voltage-gated calcium channel) can be found.