Myasthenia gravis and Lambert-Eaton syndrome are autoimmune disorders of neurological transmission that manifest with varying symptoms and severity. Diagnosis can be made through clinical and electrophysiological evaluation, however, serological lab testing can confirm diagnosis in patients with inconclusive clinical or electrophysiological results. In this episode of "Answers from the Lab" podcast, Christopher Klein, M.D., explains how Mayo Clinic Laboratories' updated, two-step approach to confirmatory testing enhances physicians’ ability to diagnose and treat with certainty.

“When we looked at every permutation and combination of the prior offerings, we learned that the best sensitivity and specificity could be obtained … by just two tasks upfront – binding first and, if positive, modulating,” Dr. Klein says. “You gain the incredible sensitivity of acetylcholine binding with the incredible specificity of the acetylcholine modulating test. That change led to a 50% drop in our false positive rates.

“Not only is the updated testing approach more accurate, but automatic reflex to second-line testing saves valuable resources,” Dr. Klein says. "We really wanted to revisit the testing algorithm in a modern era when we have advanced neurophysiologic testing and improved CT imaging to know what is the best test offering. Not only are we trying to get it right, but we want to be good stewards of the resources we have, and I think this is a very big step forward to do that right."

Listen to learn more about how updates to confirmatory testing for myasthenia gravis and Lambert-Eaton syndrome improve accuracy, equipping providers with precise information to guide treatment and elevate outcomes.

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Testing

MGMR | Myasthenia Gravis Evaluation with Muscle-Specific Kinase (MuSK) Reflex, Serum

MGLE  | Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum

Useful for:

Myasthenia Gravis Evaluation with Muscle-Specific Kinase (MuSK) Reflex, Serum (Mayo ID: MGMR)

• Diagnosis for autoimmune myasthenia gravis (MG) in adults and children
• Distinguishing autoimmune from congenital MG in adults and children
• Establishing a quantitative baseline value that allows comparison with future levels if weakness is worsening

Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum (Mayo ID: MGLE)

• Confirming the autoimmune basis of a defect in neuromuscular transmission (eg, myasthenia gravis: MG, Lambert-Eaton syndrome: LES)
• Distinguishing LES from 2 recognized autoimmune forms of MG
• Raising the index of suspicion for cancer, particularly primary lung carcinoma (N-type calcium channel antibody)
• Providing a quantitative autoantibody baseline for future comparisons in monitoring a patient's clinical course and response to immunomodulatory treatment

Specimen requirements

Myasthenia Gravis Evaluation with Muscle-Specific Kinase (MuSK) Reflex, Serum (Mayo ID: MGMR)

• Patient Preparation: Patient should have no general anesthetic or muscle-relaxant drugs in the preceding 24 hours.
• Preferred: Red top
• Acceptable: Serum gel
• Specimen Volume: 3 mL

Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum (Mayo ID: MGLE)

• Preferred: Red top
• Acceptable: Serum gel
• Specimen Volume: 3 mL
• Additional Information: Patient should have no general anesthetic or muscle-relaxant drugs in the previous 24 hours.

Performance information

Myasthenia Gravis Evaluation with Muscle-Specific Kinase (MuSK) Reflex, Serum (Mayo ID: MGMR)

• Day(s) and time(s) test performed: click here.
• Analytic time: 3 days

Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum (Mayo ID: MGLE)

• Day(s) and time(s) test performed: click here.
• Analytic time: 3 days

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