Phosphorylated Tau 217 (pTau-217), Plasma

TEST: 484390
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CPT: 83520
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Synonyms

  • 217
  • p-Tau217
  • pTau217
  • Tau

Special Instructions

This test is not approved for use in New York state.

Expected Turnaround Time

5 - 7 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Specimen Requirements

Specimen

Plasma, frozen

Volume

1 mL

Minimum Volume

0.75 mL (Note: This volume does not allow for repeat testing.)

Container

Lavender-top (EDTA) tube

Collection

Draw blood in lavender-top (EDTA) tube. Invert to mix with preservatives. Centrifuge and transfer plasma to a labeled plastic transport tube and freeze.

Storage Instructions

Freeze.

Stability Requirements

Temperature

Period

Frozen

-20°C: 14 days

-80°C: 2 months

Freeze/thaw cycles

Stable x3

Causes for Rejection

Serum specimen; improper labeling; grossly hemolyzed

Test Details

Use

This test is used to aid in the biological identification of Alzheimer's disease by measuring phosphorylated tau 217, which has been shown in the literature to be a surrogate of amyloid pathology. Additionally, pTau-217 can be used for monitoring patients on newly approved anti-amyloid therapy.

Clinical cutoff value was established using samples from a well-established patient cohort characterized with amyloid PET data. A pTau-217 value of >0.18 is a reported surrogate marker for beta amyloid pathology and can be used to facilitate biological identification of Alzheimer's disease.1 pTau-217 has also been used in clinical trials to monitor patients on anti-amyloid therapy.2,3

Limitations

This test is performed by Fujirebio Lumipulse chemiluminescent enzyme immunoassay (CLEIA). Values obtained with different methods cannot be used interchangeably. The validated limit of quantification is 0.06 pg/mL. Assay detection limit is 0.03 pg/mL.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Methodology

Fujirebio Lumipulse chemiluminescent enzyme immunoassay (CLEIA)

Reference Interval

0.00–0.18 pg/mL

Footnotes

1. Ashton NJ, Brum WS, Molfetta GD, et al. Diagnostic Accuracy of a Plasma Phosphorylated Tau 217 Immunoassay for Alzheimer Disease Pathology. JAMA Neurol. 2024 Mar 1;81(3):255-263.38252443
2. Ashton NJ, Janelidze S, Mattsson-Carlgren N, et al. Differential roles of Aβ42/40, p-tau231 and p-tau217 for Alzheimer's trial selection and disease monitoring. Nat Med. 2022 Dec;28(12):2555-2562.36456833
3. Pontecorvo MJ, Lu M, Burnham SC, et al. Association of Donanemab Treatment With Exploratory Plasma Biomarkers in Early Symptomatic Alzheimer Disease: A Secondary Analysis of the TRAILBLAZER-ALZ Randomized Clinical Trial. JAMA Neurol. 2022 Dec 1;79(12):1250-1259.36251300

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
484390 p-tau217 484391 p-tau217 pg/mL Pending
484390 p-tau217 484392 Footnotes N/A

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