Description
Lambert-Eaton myasthenic syndrome (LEMS) is associated with small cell lung cancer as a paraneoplastic phenomenon. There is a decrease in the expression of voltage gated calcium channels (VGCC) on presynaptic nerve terminals due to presence of an autoantibody. The tumour cells also express this antigen.
Indication
Lambert-Eaton myasthenic syndrome (LEMS) associated with small cell lung.
Interpretation
Presence of VGCC antibodies has a sensitivity of >90% for LEMS associated with primary lung cancer and around 40% assocaited with small cell lung cancer. Up to 40% of LEMS patients have no sign of the primary cancer on diagnosis but it develops in 2-4 years.
Assay details
Radioimmunassay: Antibodies block binding of radiolabelled w-conotoxin to membrane receptor preparations.
Restrictions
Referred test: only available to Neurology staff.
Assay range notes
Results\expressed as pM of bound toxin. Values above 100pM are considered as\ positive. Under 45pM are negative.
Turnaround time
28 days
Analysing laboratory
Churchill Hospital Department of Immunology