VGKC complex (LGI1 and CASPR2) antibody test
Quick answer: This blood test looks for antibodies against LGI1 and CASPR2, proteins linked to potassium channels on nerve cells. Doctors usually order it when they suspect autoimmune encephalitis, certain seizures or nerve over-activity disorders.
- SampleBlood
- TakesAbout 5 minutes
- Before the testNo special preparation is usually needed.
How the test is done
- 1A nurse confirms the LGI1 and CASPR2 request
- 2A vein in your arm is cleaned
- 3A needle draws a tube of blood
- 4The lab tests for each antibody separately, often by cell-based assay
What your results can mean
Reading your report
A positive result does not by itself confirm a disease, because some healthy people test positive; your doctor reads it with your symptoms and other tests.
If the result is outside the usual range
A positive LGI1 result can point to limbic encephalitis with memory loss and brief face and arm jerks, and a positive CASPR2 to nerve over-activity, pain or Morvan syndrome. A VGKC result without LGI1 or CASPR2 is often not significant.
Who usually has this test
People with new memory problems, confusion, unusual brief seizures, muscle twitching or cramps without a clear cause.
Risks and aftercare
Nothing special for the blood test; follow your doctor's advice about the symptoms themselves.
Names and options
Also called: VGKC, LGI1 antibody, CASPR2 antibody
Listed by the hospital as
- VGKC (LG1&CASPR2) ANTIBODY
Questions about this test
Why test LGI1 and CASPR2 rather than VGKC alone?
Older VGKC tests picked up antibodies that often did not matter. LGI1 and CASPR2 are the specific targets linked with disease, so testing them gives a clearer answer.
What are faciobrachial dystonic seizures?
They are very brief jerks of the face and arm on one side, sometimes many times a day. They are a typical early sign of LGI1 encephalitis.
Is LGI1 encephalitis treatable?
Yes, it often responds to immune treatment, especially when started early. Your neurologist will explain the options.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.