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Test Name:
Neuromyelitis Optica IgG Autoantibody, by ELISA, with IFA if Indicated, Serum

• SBMF No:
  42231
• Performance Lab Name:
  Mayo Medical Laboratories
• Test Mnemonic:
  NMOS
• ABN:
  Required – "Research Use Only"
• CPT Code:
  83520; If indicated, add 86255
• LOINC Code:
  19146-0
• Ref Lab Test No:
  NMOER | 60796
• Test Includes:
  NMO/AQP4-IgG by ELISA
  NMO-IgG by IFA (If indicated)
• Also Known As:
  AQP
  AQP4
  Aquaporin (-4)
  Devic's Disease antibody
  NMO Evaluation with Reflex
  NMO-IgG
  Optic Neuritix Antibody
  Optic-Spinal MS Antibody
  Transverse Myelitis Antibody
  Vision Loss Antibody
• Spec Type:
  Serum
• Spec Container:
  Gold top (SST) or Red top (serum) tube
• Pref Vol:
  2.0 mL
• Min Vol:
  1.5 mL
• Fasting:
  No
• Spec Collect:
  Routine venipuncture
• Spec Process:
  Clot 30 minutes
  Promptly centrifuge 15 minutes
  Immediately transfer serum to separate plastic tube
• Spec Store Transport:
  Refrigerated
• Spec Stability:
  72 hours room temperature (20-30°C)
  14 days refrigerated (2-8°C)
• Spec Reject:
  Grossly hemolyzed, icteric, or lipemic specimens
  Specimens other than serum
• Spec Remarks:
  Include relevant clinical information, name, phone number, mailing address, and e-mail address (if applicable) of ordering physician
• Methodology:
  Enzyme-Linked Immunosorbent Assay (ELISA)
  Indirect Immunofluorescence Assay (IFA)
• Use:
  Establishing the diagnosis of an neuromyelitis optica spectrum disorder and distinguishing one of these disorders from multiple sclerosis early in the course of disease, allowing early initiation, and maintenance, of optimal therapy
• Clinical Significance:
  

  Neuromyelitis optica (NMO, sometimes called Devic disease) is a severe, relapsing, autoimmune, inflammatory and demyelinating central nervous system disease that predominantly affects optic nerves and the spinal cord. The disorder is now recognized as a spectrum of autoimmunity targeting the astrocytic water channel aquaporin-4 (AQP4). NMO spectrum disorders (NMOSD) may involve the brain and brainstem with symptoms of encephalopathy (particularly in children). The initial symptoms may be bouts of intractable nausea and vomiting. Magnetic resonance imaging typically reveals large inflammatory spinal cord lesions involving 3 or more vertebral segments. During acute attacks, the cerebrospinal fluid contains inflammatory cells, but usually lacks evidence of intrathecal IgG synthesis. The clinical course is characterized by relapses of optic neuritis or transverse myelitis, or both.

  Prior to introducing a serological biomarker for NMO, the disorder was thought to be confined exclusively to the optic nerves and spinal cord, that the clinical course was monophasic and that NMO was a subset of multiple sclerosis (MS). The discovery of a highly specific disease marker for NMO (NMO-IgG/AQP4-IgG) helped to define the full clinical spectrum of NMOSD and to distinguish these disorders from MS. Attacks are often severe resulting in a rapid accumulation of disability (blindness and paraplegia). Within 5 years, 50% of patients lose functional vision in at least 1 eye or are unable to walk independently. Many patients with NMOSD are misdiagnosed as having MS. Importantly, the prognosis and optimal treatments for the 2 diseases differ. NMOSD typically has a worse natural history than MS, with frequent and early relapses. Treatments for NMOSD include corticosteroids and plasmapheresis for acute attacks and mycophenolate mofetil, azathioprine and rituximab for relapse prevention. Beta-interferon, a treatment promoted for MS, exacerbates NMOSD. Therefore, early diagnosis and initiation of NMO-appropriate immunosuppressant treatment is important to optimize the clinical outcome by preventing further attacks.

  Detection of AQP4-IgG by enzyme-linked immunosorbent assay allows distinction of NMOSD (65%-77% are positive) from MS (0% positive), and is indicative of a relapsing disease, mandating initiation of immunosuppression, even after the first attack, thereby reducing attack frequency and disability in the future.

• Reference Range:
  

  NMO/AQP4-IgG by ELISA
  <1.6 U/mL

  NMO-IgG by IFA
  Negative

  Interpretive Data:
  A positive value is consistent with a neuromyelitis optica (NMO) spectrum disorder and justifies initiation of appropriate immunosuppressive therapy at the earliest possible time. Positive AQP4-IgG enzyme-linked immunosorbent assay results are > or =5 units/mL. Negative results are <1.6 units/mL. Sera yielding indeterminate results (1.6-4.9 units/mL) will be reflexed to NMO-IgG indirect immunofluorescence testing for confirmation of positivity. NMO-IgG indirect immunofluorescence is positive if an NMO-specific immunostaining pattern is detected at a dilution of > or =1:60.

  Cautions:
  Seronegativity does not exclude the diagnosis of a neuromyelitis optica spectrum disorder (current seronegativity rate is 23%).

  Seronegativity may reflect immunosuppressant therapy.

  Reference:
  "Neuromyelitis Optica (NMO) Evaluation with Reflex, Serum." 2012 Online Test Catalog, Mayo Medical Laboratories, 2012. Web. 19 January 2012 <http://www.mayomedicallaboratories.com/test-catalog/Overview/60796>

• Additional Test Info:
  This test uses a reagent or kit labeled by the manufacturer as Research Use Only. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
• Day Run:
  Mon-Fri
• Time Reported:
  Within 11 days
• Test Type:
  IMMUNOLOGY