Ordering Recommendation

Differential evaluation of encephalitis of unknown origin with subacute onset of seizures, confusion, memory loss, and/or behavioral change. For extended version of this panel, refer to Autoimmune Encephalitis Extended Panel, Serum (3001431). For adults and patients with suspicion of cancer, additional evaluation of paraneoplastic autoantibodies is recommended; refer to PCCA/ANNA by IFA with Reflex to Titer and Immunoblot (2007961).




Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Enzyme-Linked Immunosorbent Assay/Quantitative Radioimmunoassay




1-8 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Serum Separator Tube (SST).

Specimen Preparation

Separate from cells ASAP or within 2 hours of collection. Transfer three 1 mL aliquots of serum to individual ARUP Standard Transport Tubes. (Min: 0.5 mL/aliquot)

Storage/Transport Temperature


Unacceptable Conditions

Amniotic fluid, ocular fluid, peritoneal fluid, synovial fluid, CSF, or plasma. Contaminated, hemolyzed, icteric, or lipemic specimens.


After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 1 month (avoid repeated freeze/thaw cycles)

Reference Interval

Test Number
Reference Interval
2004221 N-methyl-D-Aspartate Receptor Antibody, IgG, Serum with Reflex to Titer Less than 1:10
2001771 Glutamic Acid Decarboxylase Antibody 0.0-5.0 IU/mL
2004890 Voltage-Gated Potassium Channel (VGKC) Antibody, Serum
Negative 31 pmol/L or less
Indeterminate 32-87 pmol/L
Positive 88 pmol/L or greater

2003036 Aquaporin-4 Receptor Antibody Effective October 3, 2016
Negative 2.9 U/mL or less
Positive 3.0 U/mL or greater

2013320 Aquaporin-4 Receptor Antibody, IgG by IFA with Reflex to Titer, Serum Less than 1:10
2009456 Leucine-Rich, Glioma-Inactivated Protein 1 Antibody, IgG with Reflex to Titer, Serum Less than 1:10
2009452 Contactin-Associated Protein-2 Antibody, IgG with Reflex to Titer, Serum Less than 1:10

Interpretive Data

Refer to report

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)


AQP4: If AQP4 antibody IgG by ELISA is positive, then AQP4 antibody IgG by IFA will be added. If AQP4 antibody IgG by IFA is positive, then an AQP4 antibody IgG titer will be added. Additional charges apply.
VGKC: If VGKC is Indeterminate or Positive, LGI1 Antibody IgG and CASPR2 Antibody IgG will be added. 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.
NMDA: If NMDA antibody IgG is positive, then an NMDA antibody IgG titer is reported. Additional charges apply.

Hotline History


CPT Codes

83519; 83516; 86255; 86341; if reflexed add 86255 x2, if further reflexed add 86256 per titer; if reflexed add 86256; if reflexed add 86255, if further reflexed add 86256


Component Test Code* Component Chart Name LOINC
2001772 Glutamic Acid Decarboxylase Antibody 56540-8
2003121 Aquaporin-4 Receptor Antibody 68548-7
2004222 N-methyl-D-Aspartate Receptor Ab, Serum 80221-5
2004890 Voltage-Gated Potassium Channel Ab, Ser 41871-5
* 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.


Autoimmune Encephalitis Reflexive Panel, Serum (INACTIVE as of 11/15/21: Refer to 3001431 in the November Hotline)