Test Catalog

Test Id : PT217

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Phospho-Tau 217, Plasma

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Overview

Test Catalog

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

Evaluation of individuals, aged 50 years and older, presenting with cognitive impairment who are being assessed for Alzheimer disease and other causes of cognitive decline.

 

This test is not intended as a screening test for Alzheimer disease in asymptomatic individuals.

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

Chemiluminescent Enzyme Immunoassay

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

Phospho-Tau(217), P

Aliases
Lists additional common names for a test, as an aid in searching

pTau217

PhosphoTau217

Alzheimer Disease

Specimen Type
Describes the specimen type validated for testing

EDTA Plasma

Ordering Guidance

This assay is useful for individuals presenting with mild cognitive impairment or early dementia. Results must be interpreted in conjunction with other diagnostic tools such as neurological examination, neurobehavioral tests, imaging, and routine laboratory tests.

 

This assay should not be ordered for individuals younger than 50 years or in cognitively unimpaired individuals regardless of age.

 

This assay should not be used to predict the development of dementia or other neurologic conditions.

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

Collection Container/Tube: Lavender top (EDTA)

Submission Container/Tube: Plastic screw-top vial

Specimen Volume: 0.6 mL

Collection Information: Centrifuge and aliquot plasma into plastic vial. Do not submit in original tube.

Forms

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

0.5 mL

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

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

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
EDTA Plasma Refrigerated (preferred) 7 days
Frozen 7 days
Ambient 72 hours

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

Evaluation of individuals, aged 50 years and older, presenting with cognitive impairment who are being assessed for Alzheimer disease and other causes of cognitive decline.

 

This test is not intended as a screening test for Alzheimer disease in asymptomatic individuals.

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

The two main neuropathologic features observed in the brain of patients with Alzheimer disease (AD) are the presence of plaques composed of beta-amyloid (Abeta) peptides and intracellular neurofibrillary tangles containing hyperphosphorylated Tau (p-Tau) proteins. To date, positron emission tomography (PET) and cerebrospinal fluid (CSF) biomarkers are the most widely used biomarkers in clinical practice for detection of Abeta and tau pathologies. There are several PET tracers that can detect the load of Abeta fibrils in the brain (amyloid-PET). Studies have demonstrated high concordance between the in vivo uptake of these amyloid-PET tracers and the density of Abeta plaques as determined post-mortem. In CSF, Abeta42 concentrations and especially the ratios of Abeta42/Abeta40 and p-Tau181/Abeta42 concentrations correlate strongly with amyloid-PET status and AD neuropathology. Several CSF Abeta and p-Tau assays on high-performing, fully automated platforms are currently used in clinical practice. However, there is a need for accurate AD blood-based biomarkers that are easily accessible and minimally invasive.

 

Different p-Tau isoforms that are increased in the presence of amyloid pathology are detectable in plasma, including pTau181, pTau217, and pTau231. Head-to-head comparisons of assays for p-Tau181, p-Tau217, and p-Tau231 using plasma from patients with mild cognitive impairment indicate that increases in plasma p-Tau217 were superior at detecting AD pathology and predicting future development of AD dementia. Both p-Tau181 and p-Tau217 were associated with both Abeta plaques and tau tangles, with p-Tau217 showing stronger correlations with both pathologies. In addition, plasma concentrations of p-Tau217, but not p-Tau181 and p-Tau231, have been shown to increase over time in people with abnormal brain Abeta deposition correlating with brain atrophy and cognitive decline.

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 < or = 0.185 pg/mL

Intermediate 0.186-0.324 pg/mL

Positive > or = 0.325 pg/mL

Interpretation
Provides information to assist in interpretation of the test results

Negative: A normal (negative) phosphorylated Tau217 (p-Tau217) result is consistent with a negative (normal) amyloid positron emission tomography (PET) scan result. This result indicates a reduced likelihood that an individual has neuropathological changes associated with Alzheimer disease.

 

Intermediate: An intermediate p-Tau217 result cannot accurately differentiate between the presence or absence of neuropathological changes associated with Alzheimer disease. Further testing, such as amyloid positron emission tomography (PET) or cerebrospinal fluid Abeta42 and tau biomarkers, is needed to determine the likelihood of neuropathological changes associated with Alzheimer disease being present.

 

Positive: An elevated (positive) p-Tau217 result is consistent with a positive (abnormal) amyloid positron emission tomography (PET) scan result. This result is consistent with the presence of neuropathological changes associated with Alzheimer disease. In the proper clinical context this test is supportive of Alzheimer disease being related to current clinical symptoms. This test has not been demonstrated to provide information on the risk of an asymptomatic individual developing symptoms related to Alzheimer disease in the future.

 

Clinical performance of this test was established in a study of 427 individuals aged 50 years and older with mild cognitive impairment or early dementia with a 64% prevalence of amyloid pathology defined by an amyloid-positron emission tomography (PET)  and a Centiloid of > or =25. For detection of an abnormal amyloid-PET, pTau217 test sensitivity at the lower cutpoint (< or =0.185 pg/mL) was 92% and the specificity at the upper cutpoint (> or =0.325 pg/mL) was 96%. The diagnostic performance of this test has not been established in asymptomatic individuals.

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

Phosphorylated Tau217 (p-Tau217) results must be interpreted in conjunction with other diagnostic tools, such as neurological examination, neurobehavioral tests, imaging, and routine laboratory tests.

 

This assay should not be ordered for individuals younger than 50 years.

 

Elevations of p-Tau217 may be seen in individuals with impaired kidney function associated with chronic kidney disease and should be interpreted with caution in these situations.

 

False-positive or false-negative test results may occur.

 

The performance of this test was evaluated using specimens obtained from a US White population. At this time, it is uncertain if similar clinical performance will be observed in other racial and ethnic groups.

 

This assay should not be used for cognitively unimpaired (asymptomatic) individuals to predict the development of dementia or other neurological conditions.

 

The safety and effectiveness of this test have not been established for monitoring the effect of disease monitoring therapies or for predicting development of dementia or other neurologic conditions.

 

p-Tau217 concentrations have not been established to correlate with disease severity.

 

Results obtained with different assay methods or kits may be different and cannot be used interchangeably.

 

In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies or heterophile antibodies) that may cause interference in some immunoassays. Caution should be used in interpretation of results, and the laboratory should be alerted if the result does not correlate with the clinical presentation.

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

1. Arranz J, Zhu N, Rubio-Guerra S, et al. Diagnostic performance of plasma pTau 217, pTau 181, Ab 1-42 and Ab 1-40 in the LUMIPULSE automated platform for the detection of Alzheimer disease. Preprint. Res Sq. 2023;rs.3.rs-3725688. doi:10.21203/rs.3.rs-3725688/v1

2. Brum WS, Cullen NC, Janelidze S, et al. A two-step workflow based on plasma p-tau217 to screen for amyloid b positivity with further confirmatory testing only in uncertain cases. Nat Aging. 2023;3(9):1079-1090. doi:10.1038/s43587-023-00471-5

3. Mattsson-Carlgren N, Collij LE, Stomrud E, et al. Plasma biomarker strategy for selecting patients with Alzheimer disease for antiamyloid immunotherapies JAMA Neurol. 2024;81(1):69-78. doi:10.1001/jamaneurol.2023.4596

4. Janelidze S, Berron D, Smith R, et al. Associations of plasma phospho-tau217 levels with tau positron emission tomography in early Alzheimer disease. JAMA Neurol. 2021;78(2):149-156. doi:10.1001/jamaneurol.2020.4201

5. Blennow K, Galasko D, Perneczky R, et al. The potential clinical value of plasma biomarkers in Alzheimer's disease. Alzheimers Dement. 2023;19(12):5805-5816. doi:10.1002/alz.13455

6. Ashton NJ, Puig-Pijoan A, Mila-Aloma M, et al. Plasma and CSF biomarkers in a memory clinic: Head-to-head comparison of phosphorylated tau immunoassays. Alzheimers Dement. 2023;19(5):1913-1924. doi:10.1002/alz.12841

7. Mielke MM, Dage JL, Frank RD, et al. Performance of plasma phosphorylated tau 181 and 217 in the community. Nat Med. 2022;28(7):1398-1405. doi:10.1038/s41591-022-01822-2

8. Palmqvist S, Janelidze S, Quiroz YT, et al. Discriminative Accuracy of Plasma Phospho-tau217 for Alzheimer Disease vs Other Neurodegenerative Disorders. JAMA. 2020;324(8):772-781. doi:10.1001/jama.2020.12134

9. Gonzalez-Ortiz F, Kac PR, Brum WS, Zetterberg H, Blennow K, Karikari TK. Plasma phospho-tau in Alzheimer's disease: towards diagnostic and therapeutic trial applications. Mol Neurodegener. 2023;18(1):18. doi:10.1186/s13024-023-00605-8

10. Barthelemy NR, Horie K, Sato C, Bateman RJ. Blood plasma phosphorylated-tau isoforms track CNS change in Alzheimer's disease. J Exp Med. 2020;217(11):e20200861. doi:10.1084/jem.20200861

11. Jack CR, Wiste HJ, Algeciras-Schimnich A, et al. Predicting amyloid PET and tau PET stages with plasma biomarkers. Brain. 2023;146(5):2029-2044. doi:10.1093/brain/awad042

12. Karikari TK, Ashton NJ, Brinkmalm G, et al. Blood phospho-tau in Alzheimer disease: analysis, interpretation, and clinical utility. Nat Rev Neurol. 2022;18(7):400-418. doi:10.1038/s41582-022-00665-2

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

Plasma calibrator or specimen are added to particle solution. Phosphorylated Tau217 (p-Tau217) in specimens or calibrators specifically binds to anti-p-Tau217 monoclonal antibody (mouse) on the particles and antigen-antibody immunocomplexes are formed. The particles are washed and rinsed to remove unbound materials. Alkaline phosphatase (ALP)-labeled anti-Tau monoclonal antibodies (mouse) are added and specifically bind to the prior formed immunocomplexes on the particles, and additional immunocomplexes are formed. The particles are washed and rinsed to remove unbound materials. Substrate solution is added and mixed with the particles and 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy) phenyl-1,2-dioxetane disodium salt (AMPPD) contained in the substrate solution is dephosphorylated by the catalysis of ALP indirectly conjugated to particles. Luminescence (at a maximum wavelength of 477 nm) is generated by the cleavage reaction of dephosphorylated AMPPD. The luminescent signal reflects the amount of p-Tau217 in the sample.(Unpublished Mayo method)

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.

Tuesday, Thursday

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.

1 to 5 days

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

3 months

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

Rochester

Fees
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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.

83520

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
PT217 Phospho-Tau(217), P In Process
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.
217PT pTau217, P In Process
PTINT pTau217 Interpretation 69048-7

Test Setup Resources

Setup Files
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Excel | PHP Pdf | CMS Pdf

Sample Reports
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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