Voltage-Gated Calcium Channel (VGCC) Type N Antibody

Test Code

93882

CPT Codes
86596

Preferred Specimen

1 mL serum

Minimum Volume

0.5 mL

Transport Container

Plastic screw-cap vial

Transport Temperature

Frozen

Specimen Stability

Room temperature: 48 hours
Refrigerated: 48 hours
Frozen: 60 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Grossly lipemic • Grossly icteric samples • Turbid • Bacterial contamination

Methodology
Radioimmunoassay (RIA)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Tues, Thurs; Report available: 8-15 days

Reference Range

<54 pmol/L

Clinical Significance

N-type calcium channel antibodies are more highly associated with primary lung cancer than P/Q-type. One or all of the autoantibodies in the myasthenia gravis (MG)/LEMS evaluation can occur with neoplasia without evidence of neurological impairment. One or both calcium channel antibodies (P/Q and N) can occur with paraneoplastic and idiopathic cerebellar ataxia, encephalomyeloneuropathies, and autonomic neuropathy. Classical symptoms of LEMS include proximal muscle weakness, fatigability, dry mouth and impotence. When presentation is further complicated with oculobulbar weakness, these symptoms can easily be misinterpreted as MG. However, because VGCC antibodies are positive in only approximately 5% of MG patients, the measurement of these antibodies is very useful in distinguishing LEMS from MG.

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.