Test ID: AMPCC
AMPA-Receptor Antibody by CBA, Spinal Fluid
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Evaluating new onset encephalopathy encompassing 1 or more of the following: confusional states, psychosis, delirium, memory loss, hallucinations, seizures, dyssomnias
The following accompaniments should prompt suspicion for autoimmune encephalopathy:
-Headache
-Autoimmune stigmata (personal or family history, or signs of diabetes mellitus, thyroid disorder, vitiligo, poliosis [premature graying], myasthenia gravis, rheumatoid arthritis, systemic lupus erythematosus)
-History of cancer
-Smoking history (20+ pack years) or other cancer risk factors
-Inflammatory cerebrospinal fluid or isolated protein elevation
-Neuroimaging signs suggesting inflammation
Evaluating limbic encephalitis
Directing a focused search for cancer
Investigating encephalopathy appearing in the course or wake of cancer therapy, and not explainable by metastasis or drug effect
Method Name A short description of the method used to perform the test
Cell-binding assay (CBA) detects IgG specific for 2 amino-3 (5-methyl 3 oxo-1,2 oxazole 4 yl) propanoic acid receptor (AMPA-R) by indirect immunofluorescence (IFA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
AMPA Receptor Ab
Anti-AMPA
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Sterile vial
Specimen Volume: 1 mL
Additional Information: Include relevant clinical information, name, phone number, mailing address, and E-mail address (if applicable) of ordering physician
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild reject; Gross reject |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| CSF | Refrigerated (preferred) | 28 days |
| Frozen | 28 days | |
| Ambient | 72 hours |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
AMPA receptors are highly conserved mammalian ionotropic glutamate receptors that mediate most fast excitatory neurotransmission in the brain. Antibodies targeting the extracellular domains of either or both GluR 1 or GluR2 (GluA1 or GluA2) subunits have been reported in 10 patients with thymoma, breast carcinoma, or lung carcinoma (small-cell or non-small cell)-associated limbic encephalitis. Patients with limbic encephalitis present with seizures, memory loss, and mood and personality changes. Coexisting neural autoantibodies were detected in 3 of the 10 seropositive patients: CRMP 5-IgG, 1; AGNA/SOX1 IgG, 1; GAD65 antibody, 1. Antibody-depleting therapies afforded rapid improvements, but relapses were frequent after discontinuing immunotherapy. Testing of cerebrospinal fluid is helpful when serum testing is negative.
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.
Negative
Interpretation Provides information to assist in interpretation of the test results
AMPA-R-IgG is a valuable serological marker of autoimmune encephalopathy and of a patient's immune response to cancer. This autoantibody is usually accompanied by subacute neurological symptoms and signs, and is not found in healthy subjects.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A negative result does not exclude autoimmune encephalopathy or cancer.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Lai M, Hughes EG, Peng X, et al: AMPA receptor antibodies in limbic encephalitis alter synaptic receptor location. Ann Neurol 2009;65(4):424-434
Method Description Describes how the test is performed and provides a method-specific reference
Patient cerebrospinal fluid is applied to a composite slide containing transfected HEK293 cells. After incubation and washing, fluorescein-conjugated goat IgG reactive with human IgG is applied to detect bound patient IgG.(Lennon VA, Kryzer TJ, Pittock SJ, et al: IgG marker of optic-spinal multiple sclerosis binds to the aquaporin-4 water channel. J Exp Med 2005;202[4]:473-477)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Wednesday, Friday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
86255
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 61514 | AMPA-R Ab CBA, CSF | In Process |
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