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6 - 8 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
0.4 mL (Note: This volume does not allow for repeat testing.)
Red-top tube or gel-barrier tube
Serum should be separated from cells within one hour and transferred to a plastic transport tube.
Patient should have no radioactive isotopes administered 24 hours prior to venipuncture.
Nonserum specimen; gross hemolysis; gross lipemia
Measurement of P/Q-type voltage-gated calcium channel (VGCC) antibodies as an aid in the diagnosis of Lambert-Eaton myasthenic syndrome (LEMS)
Results for this test are for research purposes only by the assay's manufacturer. The performance characteristics of this product have not been established. Results should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.
This procedure may be considered by Medicare and other carriers as investigational and, therefore, may not be payable as a covered benefit for patients.
Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular transmission that affects the presynaptic release of acetylcholine.1-3 The release of acetylcholine from storage vesicles in the nerve ending is regulated by the influx of calcium through voltage-gated channels (VGCC). The impairment of acetylcholine release results in fatiguability and muscle weakness that is characteristic of the disease. Several subtypes of calcium channels have been described (T, L, N, P) based on biophysical and pharmacological properties. Of these, P subtypes are thought to be the most significant in LEMS.
LEMS is a paraneoplastic syndrome that is highly associated with small-cell lung carcinoma (SCLC). This association is thought to be due to antigenic similarity between proteins found in the tumor cells and the voltage-gated calcium channel proteins. Classic symptoms of LEMS include proximal muscle weakness, fatiguability, dry mouth, and impotence. When presentation is further complicated with oculobulbar weakness, these symptoms can be easily misinterpreted as myasthenia gravis (MG); however, because VGCC antibodies are positive in only ∼5% of MG patients, in comparison to ∼95% of LEMS patients, the measurement of these antibodies is very useful in distinguishing LEMS from MG.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|140640||VGCC Antibody||30073-1||140679||VGCC Antibody||30073-1|
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