Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum
Use
This test helps confirm the autoimmune basis of defects in neuromuscular transmission, such as myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS). It is useful for distinguishing LEMS from autoimmune forms of MG and provides a quantitative autoantibody baseline for monitoring a patient's clinical course and response to immunomodulatory treatment. MG is caused by autoantibodies binding to muscle acetylcholine receptors, while LEMS involves antibodies targeting P/Q-type calcium channels. Accurate diagnosis aids in appropriate therapeutic interventions.
Special Instructions
Specimen collection should be performed before initiating immunosuppressant therapy to avoid affecting the diagnostic sensitivity. Waiting period for patients who received radioisotopes depends on the isotope's clearance rate. Specimens must be radiation-free for testing to proceed.
Limitations
Positive results should be considered in conjunction with clinical and electrophysiological findings. The presence of antibodies is indicative of autoimmune neuromuscular disorders but does not exclude other conditions. False positives may occur in autoimmune liver disorders or post-transplant patients. Negative results do not completely exclude MG or LEMS and retesting may be necessary if clinical suspicion remains high.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 97566-4
- 97558-1
- 94705-1
- 69048-7
Result Turnaround Time
3-10 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
3 mL
Minimum Volume
2 mL
Container
Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial. Use a red top tube for collection or a serum gel tube if necessary.
Patient Preparation
For optimal antibody detection, collect specimen prior to starting immunosuppressant medication.
Causes for Rejection
Gross hemolysis, gross lipemia, and gross icterus.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 28 days |
| Frozen | 28 days |