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Autoantibody Profiles of Myasthenia Gravis, Thymoma & Lambert-Eaton Myasthenic Syndrome

Autoantibodies Aiding the Diagnosis of LES

Slide 18

July 2009

Testing for antibodies with neuronal calcium channel specificity also aids the diagnosis of Lambert-Eaton syndrome. There are 2 types of calcium channel antibodies tested for in the myasthenia gravis/Lambert-Eaton syndrome evaluation. These are of P/Q-type and N-type. P/Q-type calcium channel antibodies are positive in 95% of patients who are non-immunosuppressed and 99% of patients with cancer that have Lambert-Eaton syndrome. This antibody distinguishes Lambert-Eaton syndrome from myasthenia gravis in the appropriate clinical and electrophysiological context that I outlined earlier. Sometimes the P/Q-type calcium channel antibodies are undetectable at symptom onset and should be reevaluated at 12 months, if the disorder is clinically suspected. And, seronegativity for this antibody does not exclude a diagnosis of Lambert-Eaton syndrome.

Aiding the Diagnosis of LES


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