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Test Code GFATS Glial Fibrillary Acidic Protein Alpha Subunit Antibody, Immunofluorescence Titer Assay, Serum (Non-Orderable)


Necessary Information


Provide the following information:

-Relevant clinical information

-Ordering healthcare professional name, phone number, mailing address, and email address



Specimen Required


Only orderable as a reflex. For more information see PNEFS / Neuroimmunology Antibody Follow-up, Serum.

 

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 4 mL Serum

Collection Instructions: Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.


Useful For

Only orderable as a reflex. For more information see PNEFS / Neuroimmunology Antibody Follow-up, Serum.

 

Reporting an end titer result in serum specimens

 

Distinguishing autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy from infectious meningoencephalitis and idiopathic inflammatory central nervous system disorders, such as multiple sclerosis, vasculitis and sarcoidosis, disorders commonly considered in the differential diagnosis

 

Alerting the clinician that the patient has an immune-mediated, steroid-responsive disorder and to search for a malignancy

Testing Algorithm

If immunofluorescence assay (IFA) pattern suggests glial fibrillary acidic protein (GFAP), then the GFAP IFA titer and GFAP cell-binding assay are performed at an additional charge.

Method Name

Only orderable as a reflex. For more information see PNEFS / Neuroimmunology Antibody Follow-up, Serum.

 

Indirect Immunofluorescence Assay (IFA)

Reporting Name

GFAP IFA Titer, S

Specimen Type

Serum

Specimen Minimum Volume

Serum: 1 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Reference Values

Only orderable as a reflex. For more information see PNEFS / Neuroimmunology Antibody Follow-up, Serum.

 

<1:240

Interpretation

Seropositivity for autoantibody (positive) is supportive of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy, a treatable form of meningoencephalomyelitis. A paraneoplastic basis should be considered, according to age, sex, and other risk factors.

 

Patients who are GFAP-IgG positive have increased risk of tumor. GFAP-IgG increases the likelihood of certain malignancies being found within 2 years of symptom onset (34%). The most common malignancy found is ovarian teratoma (22%).

 

Glial fibrillary acidic protein meningoencephalomyelitis is immunotherapy responsive. GFAP-IgG positive patients have better outcomes after treatment with corticosteroids.

 

The presence of GFAP-IgG alerts the clinician that the patient has an immune-mediated, steroid-responsive disorder and directs patient care accordingly. It also alerts the clinician to search for a malignancy.

Clinical Reference

1. Fang B, McKeon A, Hinson SR, et al: Autoimmune glial fibrillary acidic protein astrocytopathy: a novel meningoencephalomyelitis. JAMA Neurol 2016;73(11):1297-1307

2. Flanagan EP, Hinson SR, Lennon VA, et al: Glial fibrillary acidic protein immunoglobulin G as biomarker of autoimmune astrocytopathy: Analysis of 102 patients. Ann Neurol 2017;81(2):298-309

3. Iorio R, Damato V, Evoli A, et al: Clinical and Immunological characteristics of the spectrum of GFAP autoimmunity: a case series of 22 patients. J Neurol Neurosurg Psychiatry 2018;89(2):138-146 doi:10.1136/jnnp-2017-316583

Day(s) Performed

Monday through Sunday

Report Available

10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

86256

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GFATS GFAP IFA Titer, S 93423-2

 

Result ID Test Result Name Result LOINC Value
605133 GFAP IFA Titer, S 93423-2