Test Details
Methodology
Immunofluorescence (IFA)
Result Turnaround Time
1 - 2 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
This test is used for evaluation of patients with suspected Neuromyelitis Optica Spectrum Disorder (NMOSD).
Limitations
The absence of AQP4 antibodies does not rule out the diagnosis of NMOSD because false-negative results may occur in the setting of immunosuppression. Occasionally, patients without detectable serum AQP4 IgG are later found to be seropositive; antibody levels increase with clinical relapse and decrease with immunosuppressive therapy. Retesting should be considered before B-cell- or antibody-targeted therapies are instituted and in patients with seronegative results who relapse.
AQP4 titers may increase but may not be predictive of relapses or attacks. AQP4 antibodies may become undetectable with immunosuppression, but this does not necessarily indicate clinical response.
Results should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure.
This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
Custom Additional Information
Testing for Neuromyelitis Optica (NMO) Spectrum should be considered in patients presenting with optic neuritis, transverse myelitis, and/or area postrema clinical syndrome, which consists of intractable hiccups or nausea and vomiting. NMOSD diagnosis is based on core clinical characteristics, antibody status, and features as detected by magnetic resonance neuroimaging. All of these components are included in the International Panel for NMO Diagnosis (IPND) 2015 revised consensus criteria.
Laboratory testing involves determining AQP4 IgG and MOG IgG serum antibody status; the presence of AQP4 or MOG IgG is confirmatory for NMOSDs in the appropriate clinical setting. Cell-based assay (CBA) detection methods are strongly recommended because of their greater sensitivity and specificity when compared with enzyme-linked immunosorbent assays (ELISAs). Patients should be tested during attacks and before beginning immunosuppressive therapy to avoid conversion to a seronegative status.
Specimen Requirements
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Serum from red-top tube
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Storage Instructions
Room temperature
Causes for Rejection
Gross hemolysis; grossly lipemic; serum separator tube (SST)
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 505295 | Anti-Aquaporin (AQP4), Serum | 63439-4 | 505296 | AQP4 Antibody, Cell-based IFA | 63439-4 | |
| Order Code | 505295 | |||||
| Order Code Name | Anti-Aquaporin (AQP4), Serum | |||||
| Order Loinc | 63439-4 | |||||
| Result Code | 505296 | |||||
| Result Code Name | AQP4 Antibody, Cell-based IFA | |||||
| UofM | ||||||
| Result LOINC | 63439-4 |
| Order Code | Order Name | Result Code | Result Name | UofM | Result LOINC | |
|---|---|---|---|---|---|---|
| Reflex 1 | 505298 | Anti-AQP4 Antibody, Titer | 505298 | Anti-AQP4 Antibody, Titer | 68548-7 | |
| Reflex 1 | ||||||
| Order Code | 505298 | |||||
| Order Name | Anti-AQP4 Antibody, Titer | |||||
| Result Code | 505298 | |||||
| Result Name | Anti-AQP4 Antibody, Titer | |||||
| UofM | ||||||
| Result LOINC | 68548-7 | |||||