Plasma
Back to Test Catalogue
pTau217, Plasma
Test ID: PTAU217 P
Test
Method
SIMOA
Method Description
This test is a single molecule assay (Simoa) using an antibody to pTau217 developed by ALZpath Inc. This test was developed, and its performance characteristics determined by BCNI. It has not been accredited by DAP and has not been approved or cleared by Health Canada or the US FDA. The test was performed in a DAP, CAP and CLIA certified laboratory and is intended for clinical purposes.
Platform
Quanterix HD
Specimens
Clinical Utility
Alzheimer’s disease (AD) is a neurodegenerative disorder hallmarked by extracellular amyloid plaques and intraneuronal neurofibrillary tangles of phosphorylated Tau (p-Tau) in the brain. The tau protein normally maintains microtubules assembly and stability of neuronal axons; however, tau protein with excessive phosphorylation can have pathological consequences. In patients with AD, aggregates of p-Tau can be detected by postmortem neuropathology evaluation or pre-mortem positron tomography (PET) imaging with specific tracers. Soluble p-Tau also accumulates in the CSF and can be detected in lumbar puncture samples, and ultra-sensitive methods including the technique used here can accurately detect p-Tau levels in the blood, which correlate well with CSF levels and with brain amyloid plaque burden. Plasma pTau217 levels correlate with amyloid-PET imaging and are more sensitive and specific than pTau181 in distinguishing AD from other neurodegenerative disorders.
Test Location
BC Neuroimmunology Lab, Room S-157, 2211 Wesbrook Mall, Vancouver BC V6T 2B5
Test Version
13-Jan-2025
Specimen
Specimens
Plasma
Collection Containers
Lavender top (EDTA)
Sample Volume
2.0 mL
Minimum Volume
0.5 mL
Patient Preparation
This test is not suitable for patients who have had a blood transfusion within 2-4 weeks, or who have had an allogenic bone marrow transplant.
Collection & Handling
Handling Information
Separate within 4 hours. Store and send frozen.
Additional Information
References:
Ashton et al., 2024. Diagnostic Accuracy of a Plasma Phosphorylated Tau 217 Immunoassay for Alzheimer Disease Pathology. JAMA Neurology. https://doi.org/10.1001/jamaneurol.2023.5319 Revised Criteria for Diagnosis and Staging of Alzheimer’s Disease: Alzheimer’s Association Workgroup. NIA-AA. Draft body text as of October 9, 2023. Noble, W., Hanger, D. P., Miller, C. C. J. & Lovestone, S. The Importance of Tau Phosphorylation for Neurodegenerative Diseases. Front. Neurol. 4, 83 (2013). Telser, J., Risch, L., Saely, C. H., Grossmann, K. & Werner, P. P-tau217 in Alzheimer’s disease. Clin. Chim. Acta 531, 100–111 (2022). Berry, K. et al. Hepatic and renal function impact concentrations of plasma biomarkers of neuropathology. Alzheimers Dement. Diagn. Assess. Dis. Monit. 14, e12321 (2022). Mielke, M. M. et al. Performance of plasma phosphorylated tau 181 and 217 in the community. Nat. Med. 28, 1398–1405 (2022). Gouda, M., Antwi-Berko, D., van Leeuwenstijn, M.S.S.A., Hussainali, Z., Bongers, B., Vanbrabant, J., in ’t Veld, S.G.J.G., Edelmayer, R.M., Stoops, E., Jeromin, A., Teunissen, C.E., Verberk, I.M.W., 2023. Plasma phosphorylated tau 217 levels are highly stable under common pre-analytical sample handling procedures. Alzheimer’s & Dementia 19, e078393. https://doi.org/10.1002/alz.078393
Stability
| Ambient | 3 days |
|---|---|
| Refrigerated | 7 days |
| Frozen | 28 days |
Additional Stability Information
240 days @ -80C
Rejection Criteria
| Hemolysis | Gross |
|---|---|
| Lipemia | Gross |
Test Version
13-Jan-2025
Performance / Interpretation
Method
SIMOA
Method Description
This test is a single molecule assay (Simoa) using an antibody to pTau217 developed by ALZpath Inc. This test was developed, and its performance characteristics determined by BCNI. It has not been accredited by DAP and has not been approved or cleared by Health Canada or the US FDA. The test was performed in a DAP, CAP and CLIA certified laboratory and is intended for clinical purposes.
Platform
Quanterix HD
Turnaround Time
18 days
Results
| Name | Units | Reference Range | Conversion Factor | |
|---|---|---|---|---|
| Negative | ng/L |
|
||
| Intermediate | ng/L |
|
||
| Positive | ng/L |
|
||
|
A test result ≤0.34 ng/L is a negative result and is consistent with a negative amyloid positron tomography (PET) scan.
A negative result indicates a low likelihood that a patient's cognitive impairment is due to Alzheimer's disease (AD).
A test result between 0.34 ng/L and 0.47 ng/L is considered intermediate. An intermediate result does not establish a diagnosis of AD or other cognitive disorder and has increased uncertainty in regard to amyloid PET positivity.
A test result > 0.47 ng/L is positive and is consistent with a positive amylold PET scan and amyloid pathology of Alzheimer's type. High pTau217 plasma levels alone do not establish a diagnosis of AD. Results should be interpreted in the context of other clinical signs and symptoms of AD.
|
||||
Test Location
BC Neuroimmunology Lab, Room S-157, 2211 Wesbrook Mall, Vancouver BC V6T 2B5
Test Version
13-Jan-2025
Interface / Setup
HL7 Interface Codes
| Order Code | Result Codes | Units |
|---|---|---|
| PTAU217 P | 65615Plasma pTau217 | ng/L |
Test Version
13-Jan-2025