REF MISC
Voltage-gated Potassium Channel Antibody (VGKC)
Performing Lab:
Referral Laboratory
Container Type:
serum gel tube or plain red-top
Specimen Type:
Serum
Preferred Volume:
4 mL
Minimum Volume:
0.5 mL
Specimen Processing:
Separate serum from cells within 1 hour. Transfer serum to an aliquot tube.
Store and Transport:
Refrigerated
Stability:
After separation from cells:
Room Temperature: 72 hours
Refrigerated: 2 weeks
Frozen: 1 month (avoid repeated freeze/thaw cycles)
Unacceptable Condition:
Plasma. Grossly lipemic or icteric specimens.
CPT Codes:
83519
Method:
Quantitative Radioimmunoassay
Reference Ranges:
Clinical Significance:
Voltage-Gated Potassium Channel (VGKC) antibodies are associated with neuromuscular weakness as found in neuromyotonia (also known as Issacs syndrome) and Morvan syndrome. VGKC antibodies are also associated with paraneoplastic neurological syndromes and limbic encephalitis; however, VGKC antibody-associated limbic encephalitis may be associated with antibodies to leucine-rich, glioma-inactivated 1 protein (LGI1) or contactin-associated protein-2 (CASPR2) instead of potassium channel antigens. A substantial number of VGKC-antibody positive cases are negative for LGI1 and CASPR2 IgG autoantibodies, not all VGKC complex antigens are known. The clinical significance of this test can only be determined in conjunction with the patient's clinical history and related laboratory testing.
Notes:
Screening test for voltage-gated potassium channel (VGKC) antibody receptor complex-associated autoantibodies. Assay does not identify contactin associated protein 2 (CASPR2) antibody or leucine-rich glioma inactivated 1 protein (LGI1) antibodies. Use to manage antibody-positive (VGKC, LGI1, or CASPR2) individual following immunotherapy and/or plasmapheresis.
Reflex Test :