Potassium channel antibody

Alternative names, keywords

Voltage-gated K channel antibody, anti VGKC, VGKC-complex antibody, LGI1 antibody, CASPR2 antibody.

Samples required

Clotted blood (gold cap, 5 mL tube). Smaller tubes are available for paediatric samples.

Test indications

Direct analysis of LGI1 and CASPR2 antibodies is now the first line investigation. Voltage gated potassium channel antibodies are available by special request.

Values > 400 pM are most commonly associated with limbic encephalitis or epilepsy syndromes. Values between 100 and 400 pM are more common in acquired neuromyotonia and Morvan’s syndrome, but can be found in patients with unrelated symptoms including some neurodegenerative disorders.

Disease associations:

Acquired neuromyotonia: 40%

Limbic encephalitis-like syndromes: not known, (both sometimes associated with thymoma or SCLC)

Test information

IgG, detected by RIA.

Direct analysis of LGI1 and CASPR2 antibodies is preferred. These antibodies target the extracellular domains of the proteins, hence can be pathogenic, and are found highly specifically in patients with immunotherapy responsive syndromes.

Reference range

0 - 69 pmol/L - negative
70 - 130 pmol/L - equivocal
>130 pmol/L - positive

Turnaround time

Referral lab quotes turnaround time of 17 days, however additional time must be allowed for packing, dispatch and delivery of sample, and return and processing of results.

Enquiries

Immunology (Referrals)