Ordering Recommendation

Aid in diagnosis of leucine-rich glioma inactivated 1 protein (LGI1) antibody disorders associated with limbic encephalitis, hyponatremia, and myoclonic movements. Disorders are rarely associated with tumors.
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 (LGI1 or 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

Test Number
Reference Interval
  CASPR2 Ab IgG CBA-IFA Screen, Serum Less than 1:10
  LGI1 Ab IgG CBA-IFA Screen, Serum Less than 1:10

Interpretive Data

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)


If LGI1 antibody IgG is positive, then LGI1 antibody IgG titer will be added. If CASPR2 antibody IgG is positive, then CASPR2 antibody IgG titer will be added. Additional charges apply.

Hotline History


CPT Codes

86255 x2; if reflexed add 86256 per titer


Component Test Code* Component Chart Name LOINC
2009453 CASPR2 Ab IgG CBA-IFA Screen, Serum 82979-6
2009457 LGI1 Ab IgG CBA-IFA Screen, Serum 82978-8
* 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.


Leucine-Rich, Glioma-Inactivated Protein 1 Antibody, IgG CBA-IFA and Contactin-Associated Protein-2 Antibody, IgG CBA-IFA with Reflex to Titers, Serum