N-methyl-D-Aspartate Receptor (NMDAR) Antibody, IgG by CBA-IFA, CSF With Reflex to Titer

Casandra

Casandra Test Code AR64820Version 1 (DRAFT)

Performing Lab

Lab ARUP LaboratoriesLab Test ID 2005164CPT Codes 86255, 86256

N-methyl-D-Aspartate Receptor (NMDAR) Antibody, IgG by CBA-IFA, CSF With Reflex to Titer

Also known as: NMDA G CSF

Clinical Use

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Use

This test is utilized to confirm the diagnosis of anti-NMDA receptor encephalitis, an autoimmune condition that primarily affects the brain. It is significant for its role in identifying antibodies associated with this condition, which can cause psychiatric symptoms, seizures, and autonomic instability. The test may also be employed to monitor treatment response in individuals who test positive for these antibodies. The presence of NMDA receptor antibodies is observed in some patients with limbic encephalitis and, potentially, without related tumors. The correlation with decreasing antibody levels may reflect a positive therapeutic response.

Special Instructions

If the NMDA CSF antibody IgG is positive, an additional titer is performed, incurring an extra charge. This test is approved for use in the state of New York and performed exclusively on CSF specimens, maximizing efficiency for detecting and semi-quantifying NMDA receptor IgG antibodies.

Limitations

A negative test result does not rule out a diagnosis of autoimmune limbic encephalitis, indicating that the results should be considered in conjunction with clinical history and other laboratory findings. The test results may also occasionally display positive findings in patients with non-autoimmune phenotypes, which requires cautious interpretation.

Test Details

New York Approved