Ordering Recommendation

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. Serum is the preferred specimen type; see Voltage-Gated Potassium Channel (VGKC) Antibody, Serum (2004890).

Mnemonic

VGKC CSF

Methodology

Quantitative Radioimmunoassay

Performed

Mon, Thu

Reported

1-8 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

CSF.

Specimen Preparation

Transfer 4 mL CSF to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Plasma. Grossly lipemic or icteric specimens.

Remarks
Stability

Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 month (avoid repeated freeze/thaw cycles)

Reference Interval

Negative 0.0-1.1 pmol/L
Positive 1.2 pmol/L or greater

Interpretive Data

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.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)

Note

Hotline History

N/A

CPT Codes

83519

Components

Component Test Code* Component Chart Name LOINC
3001388 Voltage-Gated Potassium Channel Ab, CSF 68913-3
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • VGKC Ab
  • VGKC complex
  • VGKC screen
Voltage-Gated Potassium Channel (VGKC) Antibody, CSF