ALZpath Plasma Phosphorylated Tau 217 (p-Tau 217)

Alzheimer’s disease (AD) is a neurodegenerative disorder hallmarked by extracellular amyloid-beta (AB) plaques and intracellular neurofibrillary tangles of hyperphosphorylated tau (p-tau), which lead to progressive loss of neuronal function and cell death. These pathologies can be present and developing in the brain for years before any symptoms become apparent. During this buildup there are several specific proteins that are released into the cerebrospinal fluid (CSF) that have been identified as reliable biomarkers for the diagnosis of AD.

Tau protein normally acts to stabilize the axons of neurons, but when it is hyperphosphorylated (p-tau) it becomes prone to aggregating into neurofibrillary tangles, leading to neuronal dysfunction and death. There are several variants of p-tau that have been identified as significant in AD, differentiated by the location of the phosphorylation site.

p-Tau 217 has been identified as a particularly noteworthy isoform. Levels of p-Tau 217 in both CSF and blood have been shown to be elevated in AD and increase over the course of the disease, indicating it could be a valuable tool for diagnosis.

Plasma p-Tau 217 levels correlate well with amyloid and tau PET imaging and perform as well as tests using CSF. This ALZpath p-Tau 217 assay was highly accurate in identifying amyloid-PET positive patients (AUC=.932).

Test code:

p-Tau 217

Abbreviations, alternative names:

ALZpath p-Tau 217, plasma p-Tau 217, ALZpathDx


In-house single-molecule assay (Simoa)


Laboratory developed test (LDT)


Specimen type:

EDTA plasma

Minimum volume:

0.5 mL

Preferred volume

1 mL

Rejection criteria:

Grossly hemolytic, lipemic, or icteric. If the sample arrives at room temperature.

Our offices are only able to receive samples Mon-Fri, so samples must be shipped Mon-Thur. Samples arriving over the weekend may need to be re-drawn.


Specimen collection:

Overnight fasting is recommended.
Draw blood in K2 EDTA tubes (lavender top).
Invert 8 times to ensure complete mixing.

Specimen handling:

Centrifuge EDTA tubes at 1800 - 2200 x g for 10-15 minutes.
Draw off plasma into Aliquot tubes with pipette, ensuring not to take gel or RBC (middle/bottom layers).
Store Aliquot tubes in refrigerator (2°C - 8°C) until shipping.

Specimen storage:

Plasma samples must either be refrigerated and shipped chilled within 24 hours of collection, or frozen and shipped on dry ice.


Testing frequency:

Once per week

Turnaround time:

3-10 business days

Reference range:

≤0.63 pg/mL


Laboratory developed test (LDT)

Additional Information

  • This is a laboratory developed test, its performance was determined by Neurocode USA Inc. It has not been cleared or approved by the Food and Drug Administration.

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