What is the role of voltage-gated calcium channel (VGCC) antibody testing in Lambert-Eaton myasthenic syndrome (LEMS)?

Updated: May 23, 2019
  • Author: David E Stickler, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Antibodies to voltage-gated calcium channels (VGCCs) have been reported in 75-100% of LEMS patients who have small cell lung cancer (SCLC) and in 50-90% of LEMS patients who do not have underlying cancer.

They are also found in fewer than 5% of patients with myasthenia gravis (MG), in up to 25% of patients with lung cancer without LEMS, and in some patients who do not have LEMS but have high levels of circulating immunoglobulins (eg, those with systemic lupus erythematosus or rheumatoid arthritis).

The sensitivity and specificity of the VGCC antibody assay are affected by the source of the antigen and the specific laboratory measuring the antibody.

Reports suggest that SOX1, an immunogenic tumor antigen in SCLC, may play a role in identifying LEMS patients with lung cancer. [6]


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