Ordering Recommendation

Aid in diagnosis of contactin associated protein 2 (CASPR2) antibody disorders associated with acquired neuromyotonia, limbic encephalitis, painful neuropathy, and Morvan syndrome. Use to manage antibody-positive (CASPR2) individual following immunotherapy and/or plasmapheresis.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Serum separator tube.

Specimen Preparation

Separate serum from cells within 2 hours of collection. Transfer 1 mL serum to an ARUP standard transport tube. (Min: 0.2 mL)

Storage/Transport Temperature


Unacceptable Conditions

CSF or plasma. Contaminated, hemolyzed, or severely lipemic specimens.


After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)


Semi-Quantitative Cell-Based Indirect Fluorescent Antibody




1-8 days

Reference Interval

Less than 1:10

Interpretive Data

Contactin-associated protein-2 (CASPR2) IgG antibody may occur as part of the voltage-gated potassium channel (VGKC) complex antibodies.

The presence of CASPR2 IgG antibody is associated with a wide spectrum of clinical manifestations, including acquired neuromyotonia, limbic encephalitis, painful neuropathy, and Morvan syndrome. Tumors such as thymoma, small cell lung cancer, and other rarer tumors may occur. The full spectrum of clinical disorders and tumors associated with the CASPR2 IgG antibody continues to be defined. Results should be interpreted in correlation with the patient's clinical history and other laboratory findings.

This indirect fluorescent antibody assay utilizes CASPR2 transfected cell lines for the detection and semiquantification of the CASPR2 IgG antibody.

Compliance Category

Laboratory Developed Test (LDT)


If CASPR2 antibody IgG is positive, then CASPR2 antibody IgG titer will be added. Additional charges apply.

Hotline History


CPT Codes

86255; if reflexed, add 86256


Component Test Code* Component Chart Name LOINC
2009453 CASPR2 Ab IgG CBA-IFA Screen, Serum 82979-6
* 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.


Contactin-Associated Protein-2 (CASPR2) Antibody, IgG by CBA-IFA With Reflex to Titer, Serum