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Understanding a rare disorder that often goes undiagnosed

Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder that affects the neuromuscular junction. It is characterized by impaired acetylcholine release, which leads to muscle weakness, autonomic symptoms, and hyporeflexia or areflexia. 

Early identification and confirmation of LEMS are critical for initiating appropriate patient management and determining whether additional oncologic evaluation is warranted. However, the rarity of the condition and its variable presentation can contribute to diagnostic delays or misdiagnosis.

The evaluation for voltage-gated calcium channel (VGCC) antibodies can support healthcare providers in distinguishing LEMS from other causes of neuromuscular weakness and autonomic dysfunction.

LEMS is a rare, immune-mediated neuromuscular disorder characterized by a clinical triad of signs and symptoms: proximal muscle weakness, autonomic symptoms, and hyporeflexia or areflexia.

Historically, more than half of LEMS cases are associated with an underlying cancer, often small cell lung cancer (SCLC). Studies suggest that LEMS patients with SCLC display a more rapidly progressing course of LEMS vs those with LEMS not associated with SCLC. Because LEMS symptoms can precede cancer detection by months or even years, lives may be saved by earlier diagnosis.

Testing for LEMS is important: The weakness associated with LEMS in patients with Idiopathic Autoimmune LEMS or Cancer-Associated LEMS may be treatable.

No-cost VGCC antibody testing through a Catalyst-sponsored program

To support the clinical evaluation of patients with suspected Lambert-Eaton myasthenic syndrome (LEMS), a sponsored antibody testing program is available through Catalyst Pharmaceuticals. The testing is conducted by Quest Diagnostics and includes 2 VGCC antibody assays that may aid in differentiating LEMS from other neuromuscular conditions.

Order the test

Start the diagnostic process

When LEMS is part of the differential diagnosis, VGCC antibody testing may help support clinical evaluation and help inform next steps in patient care. This sponsored program is intended to help reduce potential financial barriers and provide diagnostic insight in complex or overlapping neuromuscular presentations. 

The program may support decision-making when patients present with, but are not limited to, one or more of the following:

  • Progressive or proximal muscle weakness
  • Autonomic symptoms such as dry mouth, constipation, or erectile dysfunction
  • Inadequate or atypical response to myasthenia gravis therapies
  • Risk factors or clinical features suggestive of paraneoplastic syndrome

Results from these tests can complement clinical findings and support timely referrals or additional evaluations when warranted. 

Tests included in the sponsored VGCC antibody panel

Voltage-Gated Calcium Channel (VGCC) Type P/Q Antibody

Test code: 34057

National account number: 97518573

Clinical significance: May help differentiate LEMS from MG; associated with lung cancer and other neurologic presentations

  • Specimen: 1 mL serum (minimum 0.2 mL)
  • Transport container: Transport tube
  • Transport temperature: Frozen
  • Stability: Room temp (48 hours), refrigerated (7 days), frozen (35 days)

Voltage-Gated Calcium Channel (VGCC) Type N Antibody

Test code: 93882

National account number: 97518573

Clinical significance: May help differentiate LEMS from MG; associated with lung cancer and other neurologic presentations

  • Specimen: 1 mL serum (minimum 0.5 mL)
  • Transport container: Transport tube
  • Transport temperature: Frozen
  • Stability: Room temp (48 hours), refrigerated (48 hours), frozen (60 days)

  

How to order the sponsored LEMS antibody panel

1. Download and print the custom test requisition form

• Use the designated requisition form for this sponsored testing program

• Ensure all required fields are completed

2. Include your office fax number 

• A valid physician's office fax number is required for all orders to enable results delivery and program tracking

3. Collect specimens according to test-specific requirements

• Refer to the VGCC P/Q-type and N-type antibody test instructions

• Follow instructions for specimen volume, transport temperature, and stability guidelines

4. Submit the completed requisition with the specimen(s)

• Be sure to follow the specimen handling instructions carefully to ensure accurate results

• Testing is offered at no cost through the Catalyst-sponsored program ONLY when ordered using the specified codes and account number

Order Test

Questions about ordering or eligibility? We’re here to help.

If you have questions about test ordering, logistics, or panel details, please contact contact us 

Contact us

About Catalyst Pharmaceuticals 

Catalyst Pharmaceuticals, Inc. is a biopharmaceutical company committed to improving the lives of patients with rare diseases. With a proven track record of bringing life-changing treatments to the market, we focus on in-licensing, commercializing, and developing innovative therapies. Guided by our deep commitment to patient care, we prioritize accessibility, ensuring patients receive the care they need through a comprehensive suite of support services designed to provide seamless access and ongoing assistance. Catalyst maintains a well-established US presence while actively seeking to expand its global commercial footprint through strategic agreements.

For more information, please visit Catalyst's website at www.catalystpharma.com

Disclaimer

This sponsored testing program is intended to support the diagnostic evaluation of patients with suspected Lambert-Eaton myasthenic syndrome (LEMS). Testing is performed independently by Quest Diagnostics in its CLIA-certified laboratories under standard clinical protocols. Catalyst Pharmaceuticals provides financial sponsorship for the program but does not receive identifiable patient information and does not influence testing procedures, interpretation, or outcomes.

Participation in this program does not require the use of any specific therapy or product. All clinical decisions, including whether to order testing and how to act on test results, are made solely at the discretion of the ordering clinician. The tests offered through this program are intended to support, not replace, the clinical judgment of qualified medical professionals. 

Sources

Titulaer, M, et al. Epidemiology and clinical aspects of Lambert–Eaton myasthenic syndrome. Neurology 2011;77(4):387–398. doi:10.1212/WNL.0b013e3182270442 

Gilhus, N, & Verschuuren, J. Myasthenia gravis and Lambert-Eaton myasthenic syndrome. The Lancet Neurology 2015;14(10):1023–1036

Lennon, V, et al. Autoantibodies to calcium channels in the Lambert-Eaton myasthenic syndrome. New England Journal of Medicine 1989;320(9):564–568

American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM), Lambert-Eaton Myasthenic Syndrome (LEMS). Accessed May 2025

Sanders, D, et al. Lambert-Eaton Myasthenic Syndrome: Diagnostic Approaches and Testing Algorithms. Muscle & Nerve 2018;57(5):737–743. doi: 10.1002/mus.26032

National Organization for Rare Disorders (NORD). Lambert-Eaton Myasthenic Syndrome. 

Titulaer M, Lang B, Verschuuren J. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. The Lancet Neurology 2011;10(12):1098-1107.

Titulaer M, Lang B, Verschuuren J. Lambert-Eaton myasthenic syndrome: from clinical characteristics to therapeutic strategies. The Lancet Neurology 2011;Appendix:1-4.

Anderson C, Guidon A, Khan F, et al. Case report of Lambert Eaton myasthenic syndrome in a patient with small cell lung cancer on immune checkpoint inhibitor therapy. OBM Neurobiology 2021;5(1):1-9

Lipka A, Boldingh M, van Zwet E, et al. Long-term follow-up, quality of life, and survival of patients with Lambert-Eaton myasthenic syndrome. Neurology 2020;94(5):e511-e520

Wirtz P, Smallegange T, Wintzen A, Verschuuren J. Differences in clinical features between the Lambert-Eaton myasthenic syndrome with and without cancer: an analysis of 227 published cases. Clinical Neurology and  Neurosurgery 2002;104(4):359-363

Yoon C, Owusu-Guha J, Smith A, Buschur P. Amifampridine for the management of Lambert-Eaton myasthenic syndrome: a new take on an old drug. Annals of Pharmacotherapy 2020;54(1):56-63.

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