P/Q-Type Calcium Channel Antibody, Serum
Use
The test is useful for confirming a diagnosis of Lambert-Eaton syndrome and implicating autoimmunity as a disease-causing mechanism in patients with complex neurologic presentations, particularly in those with a history of cancer. It is also used for implicating autoimmunity as the basis of limbic encephalitis, cerebellar ataxia, myelopathy, peripheral neuropathy, or autonomic neuropathy. However, this test is not useful as a general screening test for cancer.
Special Instructions
The test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, due to potential assay interference. Specimens will be screened for radioactivity prior to analysis and held for a week if found radioactive, only to be assayed if radioactivity sufficiently declines.
Limitations
The test is not offered as a standalone test but is included in specific profiles for diagnosing neurological autoimmunity, usually in paraneoplastic contexts. High-dose intravenous IgG therapy may cause false-lowering or negative values. Plasma specimens can yield false-positive results. The influence of myeloma M proteins is uncertain. The test may also be affected by assay interference from radioisotopes.
New York Approved
Methodology
Immunoassay (RIA)
Biomarkers
LOINC Codes
- 94705-1
- 94705-1
Result Turnaround Time
3-7 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
Not provided
Minimum Volume
0.5 mL
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 28 days |
| Frozen | 28 days |