Test Catalog

Test Id : GFATC

Not Orderable

Glial Fibrillary Acidic Protein Alpha Subunit Antibody, Immunofluorescence Titer Assay, Spinal Fluid

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

Reporting an end titer result in spinal fluid specimens

 

Distinguishing, in spinal fluid, autoimmune GFAP astrocytopathy from infectious meningoencephalitis and idiopathic inflammatory central nervous system (CNS) 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
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If immunofluorescence assay (IFA) pattern suggests GFAP, then GFAP IFA titer and GFAP cell-binding assay (CBA) are performed at an additional charge.

Method Name
A short description of the method used to perform the test

Only orderable as a reflex. For more information, see:

DMC2 / Dementia Autoimmune Evaluation, Spinal Fluid

ENC2 / Encephalopathy Autoimmune Evaluation, Spinal Fluid

EPC2 / Epilepsy Autoimmune Evaluation, Spinal Fluid

MAC1 / Autoimmune Myelopathy Evaluation, Spinal Fluid

 

Indirect Immunofluorescence Assay (IFA)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

GFAP IFA Titer, CSF

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If immunofluorescence assay (IFA) pattern suggests GFAP, then GFAP IFA titer and GFAP cell-binding assay (CBA) are performed at an additional charge.

Specimen Type
Describes the specimen type validated for testing

CSF

Necessary Information

Provide the following information:       

-Relevant clinical information

-Ordering provider name, phone number, mailing address, and e-mail address

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Only orderable as a reflex. For more information, see:

DMC2 / Dementia Autoimmune Evaluation, Spinal Fluid

ENC2 / Encephalopathy Autoimmune Evaluation, Spinal Fluid

EPC2 / Epilepsy Autoimmune Evaluation, Spinal Fluid

MAC1 / Autoimmune Myelopathy Evaluation, Spinal Fluid

 

Container/Tube: Sterile vial

Specimen Volume: 2 mL

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
CSF Refrigerated (preferred) 28 days
Frozen 28 days
Ambient 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Reporting an end titer result in spinal fluid specimens

 

Distinguishing, in spinal fluid, autoimmune GFAP astrocytopathy from infectious meningoencephalitis and idiopathic inflammatory central nervous system (CNS) 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
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If immunofluorescence assay (IFA) pattern suggests GFAP, then GFAP IFA titer and GFAP cell-binding assay (CBA) are performed at an additional charge.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Antibody targeting glial fibrillary acidic protein (GFAP)-IgG is a biomarker of a subacute and progressive autoimmune meningitis, encephalitis, and myelitis that can mimic multiple sclerosis (MS) or other idiopathic inflammatory central nervous system (CNS) disorders such as sarcoidosis. Neurological manifestations include headache, optic neuropathy, transverse myelitis, cognitive decline, and cerebellar ataxia. Cerebrospinal fluid (CSF) is inflammatory. Cranial magnetic resonance (MR) imaging reveals linear perivascular enhancement oriented radially to ventricles. A paraneoplastic neurological context is common. Reported neoplasms accompanying neurological symptoms include adenocarcinomas (prostate and gastroesophageal), myeloma, melanoma, colonic carcinoid, parotid pleomorphic adenoma and teratoma. If GFAP-IgG is detected by immunofluorescence assay (IFA), it is reflexed to a test for the alpha isoform of GFAP (GFAPalpha-IgG) by cell based assay.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Only orderable as a reflex. For more information, see:

DMC2 / Dementia Autoimmune Evaluation, Spinal Fluid

ENC2 / Encephalopathy Autoimmune Evaluation, Spinal Fluid

EPC2 / Epilepsy Autoimmune Evaluation, Spinal Fluid

MAC1 / Autoimmune Myelopathy Evaluation, Spinal Fluid

 

<1:2

Interpretation
Provides information to assist in interpretation of the test results

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%).

 

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

 

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

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Clinical Reference
Recommendations for in-depth reading of a clinical nature

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

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;81:298-309

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 Feb;89(2):138-146 doi:10.1136/jnnp-2017-316583

Method Description
Describes how the test is performed and provides a method-specific reference

The patient's sample is tested by a standardized indirect immunofluorescence assay (IFA) that uses a composite frozen section of mouse cerebellum, kidney, and gut tissues. After incubation with sample and washing, fluorescein-conjugated goat antihuman IgG is applied. Neuron-specific autoantibodies are identified by their characteristic fluorescence staining patterns. Samples that are scored positive for any neuronal nuclear or cytoplasmic autoantibody are titrated to an endpoint. Interference by coexisting non-neuron-specific autoantibodies can usually be eliminated by serologic absorption.(Yu Z, Kryzer TJ, Griesmann GE, et al: CRMP-5 neuronal autoantibody: marker of lung cancer and thymoma-related autoimmunity. Ann Neurol 2001;49:146-154)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

10 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

28 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

86256

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
GFATC GFAP IFA Titer, CSF 93421-6
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
605134 GFAP IFA Titer, CSF 93421-6

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | PHP Pdf | CMS Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports