Test ID: P1433
14-3-3 Protein, 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
Evaluation of patients with rapidly progressive dementia to establish the diagnosis of Creutzfeldt-Jakob disease
Method Name A short description of the method used to perform the test
Immunochemiluminometric Assay (ICMA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
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.
Collection Container/Tube: Sterile vial
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Obtain aliquot from second collection vial.
2. Immediately place aliquot on ice.
Additional Information:
1. Specimens that have not been kept refrigerated, or which have been tested for other analytes previously, may give a false-positive result.
2. Hemolyzed specimens will give false-positive results. Specimens should be centrifuged to remove any red cells before shipping. The test will be canceled if there is any level of hemolysis present.
Forms: If not ordering electronically, submit a General Request Form (Supply T239) with the specimen.
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 reject; Gross reject |
| Lipemia | NA |
| Icterus | NA |
| 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) | 7 days |
| Frozen | 90 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
The 14-3-3 proteins are a group of highly conserved proteins composed of several isoforms that are involved in the regulation of protein phosphorylation and mitogen-activated protein kinase pathways. They exist in vivo as dimers of the various isoforms with apparent molecular mass of 30 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis and 60 kDa on gel chromatography. Sequence homology among the various isoforms ranges from 22% to100%. The beta, gamma, and theta isoforms are found in tissues of the nervous system.
Detectable 14-3-3 protein in the cerebrospinal fluid (CSF) is indicative of substantial, relatively rapid neuronal destruction. Increased CSF concentrations of 14-3-3 proteins have been described in patients with various forms of Creutzfeldt-Jakob disease (CJD), some other rapidly progressive dementias, and a large range of other vascular, inflammatory, neoplastic, and metabolic central nervous system (CNS) disorders (see "Cautions"), which can be associated with significant and rapid neuronal destruction.
The main clinical use of 14-3-3 measurements is in the differential diagnosis of dementia, in particular to distinguish CJD and its variants from other dementias. The most common forms of dementia (progressive multi-infarct dementia and Alzheimer disease) are uncommonly associated with elevated CSF levels of 14-3-3, presumably because of their slow pace of progression.
CJD is an incurable neurodegenerative disease caused by accumulation of self-catalytically malfolded endogenous prion proteins in the CNS. Its cause is most commonly sporadic, but it can be inherited (mutations that predispose to malfolding) or acquired (iatrogenic transmission by infected human tissues or tissue extracts or surgical procedures, or by ingestion of some animal products that contain malfolded prion proteins).
The diagnosis of CJD is highly complex and involves clinical history and neurologic examination, electroencephalographs (EEG), magnetic resonance imaging (MRI), and exclusion of other possible causes of dementia, in addition to CSF examination. Several, slightly different scoring systems are in use to integrate these parameters into a final diagnosis of possible, probable, or definite CJD. The most widely accepted of these scoring systems is the WHO set of diagnostic criteria for sporadic CJD from 1998 (see "Interpretation").
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.
Normal: <1.5 ng/mL
Elevated: > or =1.5 ng/mL; compatible with, but not diagnostic of, Creutzfeldt-Jakob disease
Interpretation Provides information to assist in interpretation of the test results
A concentration of 14-3-3 protein in cerebrospinal fluid (CSF) of > or =1.5 ng/mL supports the diagnosis of Creutzfeldt-Jakob disease (CJD) in patients who have been carefully preselected based on various diagnostic criteria. CSF 14-3-3 measurement is particularly helpful in sporadic CJD, where it is used as 1 of several diagnostic criteria.
Sporadic CJD World Health Organization (WHO) diagnostic criteria from 1998:
1. Definitive CJD:
-Neuropathological diagnosis by standard techniques AND/OR immunohistochemistry AND/OR Western blot confirmed protease-resistant prion protein AND/OR presence of scrapie-associated fibrils
2. Probable CJD:
-Progressive dementia
-At least 2 of the following symptoms:
- Myoclonus, pyramidal/extrapyramidal, visual or cerebellar, akinetic mutism
-Positive electroencephalographs (EEG) (periodic epileptiform discharges) AND/OR positive CSF 14-3-3 protein and <2 years disease duration
-No alternate diagnosis
3. Possible CJD:
-Progressive dementia
-At least 2 of the following symptoms:
- Myoclonus, pyramidal/extrapyramidal, visual or cerebellar, akinetic mutism
-No supportive EEG and <2 years disease duration
Recently proposed, but not yet universally accepted, amendments to these criteria center on including magnetic resonance imaging (MRI) high-signal abnormalities in caudate nucleus and/or putamen on diffusion-weighted imaging (DWI) or fluid attenuated inversion recovery (FLAIR) as diagnostic criteria for probable CJD.
The USA Center of Disease Control and Prevention supports these modified WHO criteria as of 2010 (http://www.cdc.gov/ncidod/dvrd/cjd/diagnostic_criteria.html).
There is no established role for 14-3-3 measurement in the diagnosis of acquired or inherited CJD.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Hemolyzed specimens will be rejected. Hemolysis causes falsely-elevated 14-3-3 results. The 14-3-3 concentrations in 82 visibly blood-tinged cerebrospinal fluid (CSF) specimens were up to 281 ng/mL, with 74 specimens (90.2%) showing levels above the cutoff.
In addition, specimens may be determined to be unsuitable for testing if any of the following conditions are observed:(1,2)
-Macroscopically hemorrhagi
-Xanthochromic
-RBC counts >500 cells per mcL
-WBC counts >10 cells per mcL
The Mayo Clinic 14-3-3 assay is a quantitative assay for 14-3-3. All other assays are currently based on qualitative or semiquantitative assessment of 14-3-3 Western blots of CSF specimens. Results of diagnostic 14-3-3 studies performed in other laboratories, therefore, cannot be compared directly with the Mayo Clinic 14-3-3 test results. However, the published literature suggests comparable sensitivity and specificity ranges between the Mayo assay and Western blot assays.
Regardless of the method used, measurement of 14-3-3 protein in CSF should not be relied upon exclusively to establish the diagnosis of Creutzfeldt-Jakob disease (CJD). Increased concentrations of 14-3-3 protein in CSF have been described in a variety of central nervous system (CNS) diseases other than CJD that are associated with relative rapid (days to months, rather than months to years) destruction of significant amounts of CNS neuronal tissue. Published examples include: infectious encephalitides, transverse myelitis, stroke, intracerebral and subarachnoid hemorrhage, rapidly progressive vascular dementia, various metabolic and anoxic encephalopathies, severe acute CNS episodes of multiple sclerosis, cerebral vasculitides and angiopathies, mitochondrial encephalomyelopathies, CNS storage diseases, widespread or rapidly growing primary or secondary CNS and leptomeningeal tumors, and, rarely, Alzheimer disease and other primary dementias.
Supportive Data
A total of 950 cerebrospinal fluid (CSF) specimens, including 14 from patients with definite (autopsy-proven) Creutzfeldt-Jakob disease (CJD), were tested for 14-3-3 protein. Using the cutoff from receiver operating characteristic curve (ROC) analysis, the sensitivity was 78.6% and specificity was 96.7%. This compares to neuron-specific enolase (NSE), which at a cutoff of 43 ng/mL had sensitivity of 78.6% and specificity of 94.0%. In another group of 30 clinically highly-possible or probable CJD cases without histological confirmation, NSE was elevated in 25 (83.3%) and 14-3-3 in 21 (70.0%).
In 235 CSF specimens sent in for RBC and WBC counting (CJD was not suspected) the specificity was 94.5%. The 13 specimens that had elevated 14-3-3 results were from patients with disorders known to elevate CSF 14-3-3, such as Guillain-Barre syndrome and viral encephalitis.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Day IN, Thompson RJ: Levels of immunoreactive aldolase C, creatine kinase-BB, neuronal and non-neuronal enolase, and 14-3-3 protein in circulating human blood cells. Clin Chim Acta 1984;136:219-228
2. Collins S, Boyd A, Fletcher A, et al: Creutzfeldt-Jakob disease: diagnostic utility of 14-3-3 protein immunodetection in cerebrospinal fluid. J Clin Neurosci 2000;7:203-208
3. Preissner CM, Aksamit AJ, Parisi JE, Grebe SK: Development and validation of an immunochemiluminometric assay for 14-3-3 protein. Clin Chem 2009;55(S6):page A199; abstract D-149
4. Collins S, Boyd A, Fletcher A, et al: Creutzfeldt-Jakob disease: diagnostic utility of 14-3-3 protein immunodetection in cerebrospinal fluid. Clin Neuroscience 2000;7:203-208
5. Burkhard PR, Sanchez JC, Landis T, et al: CSF detection of the 14-3-3 protein in unselected patients with dementia. Neurology 2001;56:1528-1533
6. Aksamit AJ, Preissner CM, Homburger HA: Quantitation of 14-3-3 and neuron-specific enolase proteins in CSF in Creutzfeldt-Jakob disease. J Neurol 2001;57:728-730
7. Castellani RJ, Colucci M, Xie Z, et al: Sensitivity of 14-3-3 protein test varies in subtypes of sporadic Creutzfeldt-Jakob disease. Neurology 2004;63:436-442
Method Description Describes how the test is performed and provides a method-specific reference
The 14-3-3 protein is measured in an immunochemiluminometric assay. The patient specimen is incubated with a monoclonal antibody directed against all 14-3-3 isoform coated on white microtiter plate wells. After washing, a second monoclonal antibody directed against the theta/tau isoforms, labeled with an acridinium ester is added. The amount of label subsequently bound to the wells is counted in a microtiter plate luminometer that calculates the amount of 14-3-3 present in the specimen.(Preissner CM, Aksamit AJ, Parisi JE, Grebe SK: Development and validation of an immunochemiluminometric assay for 14-3-3 protein. Clin Chem 2009;55[S6]: page A199; abstract D-149. Poster available on request)
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.
Monday, Thursday; 1 p.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.
83520
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 |
|---|---|---|
| 82528 | 14-3-3 Protein, CSF | 36924-9 |
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