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Order Code PT217 Phospho-Tau 217, Plasma

Additional Codes

Epic   LAB66844ia


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


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.


Secondary ID

621635

Useful For

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

Chemiluminescent Enzyme Immunoassay

Reporting Name

Phospho-Tau(217), P

Specimen Type

EDTA Plasma

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
EDTA Plasma Refrigerated (preferred) 14 days
  Frozen  90 days
  Ambient  72 hours

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Clinical Information

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

Negative: ≤0.185 pg/mL

Intermediate: 0.186-0.324 pg/mL

Positive: ≥0.325 pg/mL

Clinical Reference

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

Day(s) Performed

Monday through Friday

Report Available

1 to 3 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

84393

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PT217 Phospho-Tau(217), P 104663-0

 

Result ID Test Result Name Result LOINC Value
217PT pTau217, P 104663-0
PTINT pTau217 Interpretation 69048-7