Neuromyelitis Optica (NMO)/Aquaporin-4-IgG Fluorescence-Activated Cell Sorting (FACS) Assay, Spinal Fluid
Use
This test is critical for diagnosing neuromyelitis optica spectrum disorder (NMOSD) and autoimmune AQP4 channelopathy. It helps distinguish NMOSD from multiple sclerosis (MS) early in the disease course. NMOSD is a severe, relapsing autoimmune inflammatory condition targeting the optic nerves and spinal cord. Early and accurate diagnosis is crucial for commencing appropriate NMOSD-specific immunosuppressant therapy to prevent further attacks and improve prognosis.
Special Instructions
Consider serum testing if cerebrospinal fluid (CSF) tests negative and NMOSD is still suspected. The FACS assay is used, and if positive, additional titer testing may be performed. Physicians should inform the laboratory about relevant clinical details when ordering.
Limitations
A negative test result does not exclude NMOSD diagnosis, as AQP4-IgG antibodies might be undetectable during or after treatment for acute attack or prevention. The specificity for nonorgan-specific IgG autoantibodies is higher in CSF compared to serum, aiding in differential diagnosis between NMOSD and other conditions.
New York Approved
Methodology
Cell-based / Cytometry (Flow Cytometry)
Biomarkers
LOINC Codes
- 46718-3
- 46718-3
Result Turnaround Time
5-8 days
Related Documents
For more information, please review the documents below
Specimen
Cerebrospinal Fluid
Volume
3 mL
Minimum Volume
2 mL
Container
Sterile vial
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 28 days |
| Frozen | 28 days |