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HelpTest Code CCPQ P/Q-Type Calcium Channel Antibody, Serum
Ordering Guidance
The profile test should not be requested in patients who have recently received radioisotopes, therapeutically or diagnostically, because of potential assay interference. The specific waiting period before specimen collection will depend on the isotope administered, the dose given, and the clearance rate in the individual patient. Specimens will be screened for radioactivity prior to analysis. Radioactive samples received in the laboratory will be held 1 week and assayed if sufficiently decayed or canceled if radioactivity remains.
Specimen Required
Only orderable as part of a profile. For more information see:
PAVAL / Paraneoplastic, Autoantibody Evaluation, Serum
MGLE / Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum
MDS2 / Movement Disorder, Autoimmune Evaluation, Serum
PNEFS / Neuroimmunology Antibody Follow-Up, Serum
Useful For
Confirming a diagnosis of Lambert-Eaton syndrome
Implicating autoimmunity as a disease-causing mechanism in patients with complex neurologic presentations, particularly in those with a history of cancer
Implicating autoimmunity as the basis of limbic encephalitis, cerebellar ataxia, myelopathy, peripheral neuropathy, or autonomic neuropathy
This test is not useful as a general screening test for cancer.
Method Name
Only orderable as part of a profile. For more information see:
PAVAL / Paraneoplastic, Autoantibody Evaluation, Serum
MGLE / Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum
MDS2 / Movement Disorder, Autoimmune Evaluation, Serum
PNEFS / Neuroimmunology Antibody Follow-Up, Serum
Radioimmunoassay (RIA)
Reporting Name
P/Q-Type Calcium Channel AbSpecimen Type
SerumSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Clinical Information
This test is not offered as a standalone test but is included in the following test procedures as an aid for diagnosis of neurological autoimmunity, usually in a paraneoplastic context.
-MGLE / Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum
-MDS2 / Movement Disorder, Autoimmune Evaluation, Serum
P/Q-type calcium channels regulate neurotransmitter release at motor nerve terminals and are involved in central neurotransmission.
A snail venom toxin, omega conopeptide MVIIC, is a specific high-affinity antagonist for P/Q-type channels.
Autoantibodies directed against extracellular epitopes of P/Q-type calcium channels are implicated as the effectors of the Lambert-Eaton myasthenic syndrome (LES).
These antibodies generally reflect an immune response against cancer.
P/Q-type calcium channel binding antibodies are found in 95% of nonimmunosuppressed patients with LES (100% of those with cancer) and in 20% of patients who have encephalomyeloneuropathies related to carcinoma of lung, breast, or ovary.
Reference Values
Only orderable as part of a profile. For more information see:
PAVAL / Paraneoplastic, Autoantibody Evaluation, Serum
MGLE / Myasthenia Gravis/Lambert-Eaton Myasthenic Syndrome Evaluation, Serum
MDS2 / Movement Disorder, Autoimmune Evaluation, Serum
PNEFS / Neuroimmunology Antibody Follow-Up, Serum
≤0.02 nmol/L
Interpretation
Values greater than 0.02 nmol/L are consistent with neurologic autoimmunity and suggest a paraneoplastic basis.
Values in nonimmunosuppressed patients with Lambert-Eaton syndrome are usually greater than 0.1 nmol/L.
Cautions
High-dose intravenous IgG therapy may cause false-lowering of (or negative) values.
Plasma specimens can yield false-positive results.
The influence of myeloma M proteins is uncertain.
Method Description
High voltage-activated calcium channels of P/Q-type (ie, high affinity receptors for omega-peptide MVIIC) are solubilized from porcine cerebral cortical membranes in detergent and are complexed with (125)I-labeled omega-conopeptide-MVIIC. After incubating patient sample with labeled receptors, anti-human IgG is added to form an immunoprecipitate. The amount of (125)I-labeled receptors in the immunoprecipitate is measured using a gamma-counter. The amount of gamma emission in the precipitate is proportional to the amount of CCPQ-IgG in the sample. Results are reported as units of precipitated antigen (nMol) per L of patient sample.(Griesmann GE, Kryzer, TJ, Lennon VA: Autoantibody profiles of myasthenia gravis and Lambert-Eaton myasthenic syndrome. In: Rose NR, Hamilton RG, Detrick B, eds. Manual of Clinical and Laboratory Immunology. 6th ed. ASM Press; 2002:1005-1012; Jones AL, Flanagan EP, Pittock SJ, et al. Responses to and outcomes of treatment of autoimmune cerebellar ataxia in adults. JAMA Neurol. 2015;72[11]:1304-1312 doi:10.1001/jamaneurol.2015.2378)
Day(s) Performed
Monday through Sunday
Report Available
3 to 7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86596
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CCPQ | P/Q-Type Calcium Channel Ab | 94349-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 81185 | P/Q-Type Calcium Channel Ab | 94349-8 |