The p-tau217 blood test is an advancement for neurological health, particularly for Alzheimer’s disease. It measures specific protein changes in the blood, less invasive than traditional approaches. This test helps understand and address Alzheimer’s pathology earlier, improving diagnostic accuracy and accessibility for a condition affecting millions.
Understanding P-tau217
Tau protein stabilizes brain cell structure by supporting microtubules, which transport substances within neurons. In Alzheimer’s disease, tau undergoes an abnormal modification called hyperphosphorylation, where phosphate groups attach. This disrupts tau’s function, causing it to detach from microtubules and aggregate into neurofibrillary tangles, a hallmark of Alzheimer’s.
P-tau217 is tau protein phosphorylated at threonine 217. This modification is strongly linked to Alzheimer’s pathology and is a highly specific biomarker. Elevated p-tau217 in the blood associates with amyloid plaques in the brain, another characteristic of Alzheimer’s. Research indicates p-tau217 levels can rise years before cognitive symptoms, making it a promising tool for early detection and monitoring.
P-tau217 shows superior accuracy in distinguishing Alzheimer’s disease from other neurodegenerative conditions compared to other phosphorylated tau variants like p-tau181. Its levels correlate with both amyloid-beta pathology and tau changes observed in the brain via PET scans. A single p-tau217 blood measurement provides insights into two key aspects of Alzheimer’s pathology, offering a simpler alternative to complex and costly diagnostic methods.
The Cost of the Test
The cost of a p-tau217 blood test varies by laboratory, geographic location, and whether it’s for research or clinical use. Examples include:
LucentAD’s p-tau217 test: around $195.
WellMind p-Tau217 from ADx Health: $495.
ALZpath pTau217 assay: $200 to $500.
C2N Diagnostics’ PrecivityAD2 (combines p-tau217 with other biomarkers): around $1,200.
Prices are influenced by several factors. Proprietary assays, detection technology, and required validation contribute to the expense. Tests for research or clinical use have different pricing and availability. New technologies and increased competition could influence future pricing.
Many p-tau217 blood tests lack consistent Medicare or private insurer coverage. However, the landscape is evolving. The first blood test for Alzheimer’s disease, the Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio, received FDA clearance in May 2025. This clearance should lead to Medicare and private insurer coverage, increasing patient accessibility.
Some providers, like C2N Diagnostics, offer financial assistance for tests not yet covered. Studies suggest p-tau217 testing could reduce overall diagnostic costs by making more expensive methods like amyloid PET and CSF testing more efficient.
Accessing the Test
A p-tau217 blood test typically requires a physician’s order. Neurologists or specialists often initiate these tests for individuals aged 55+ experiencing cognitive symptoms, evaluating for Alzheimer’s or other cognitive decline causes. General practitioners may also be involved in initial assessment and referral. The Alzheimer’s Association is developing guidelines for appropriate clinical use.
P-tau217 test availability is expanding, with several companies offering them. These include:
Labcorp
ALZpath
C2N Diagnostics
Fujirebio Diagnostics
Quest Diagnostics
ADx Health
Some tests are for clinical use, others for research or have received FDA Breakthrough Device Designation. Labcorp launched its standalone pTau217 test in March 2024 for clinical use and clinical trial monitoring.
The test involves a blood draw at a local lab or clinic. Collection kits can be sent home, with draws performed in-clinic or at a local site. Results typically arrive within 3 to 10 business days. While the first FDA-cleared blood test for Alzheimer’s was cleared in May 2025, other p-tau217 tests are laboratory-developed. Their performance characteristics are determined by individual labs and are not FDA-cleared or approved.
Interpreting Your Results
Interpreting p-tau217 blood test results involves understanding biomarker levels against established cut-offs. Results typically indicate negative, intermediate, or positive p-tau217 levels, correlating with amyloid pathology likelihood. A negative result suggests reduced likelihood of Alzheimer’s neuropathological changes, consistent with a normal amyloid PET scan. Conversely, an elevated or positive p-tau217 indicates a high likelihood of amyloid pathology, consistent with an abnormal amyloid PET scan.
An intermediate result means the test cannot definitively differentiate Alzheimer’s-related neuropathological changes. In such cases, further testing like an amyloid PET scan or cerebrospinal fluid (CSF) analysis may clarify the diagnosis. These blood tests are not standalone diagnostic tools; they are part of a comprehensive evaluation including medical history, cognitive assessments, and other clinical findings.
Healthcare professionals, especially neurologists, integrate biomarker results with a broader clinical picture for accurate diagnosis and patient care. While a positive p-tau217 test indicates a high likelihood of amyloid pathology, it does not definitively diagnose Alzheimer’s alone. Discussing results with a healthcare provider is essential for accurate interpretation, understanding health implications, and potential next steps, including further diagnostic tests or treatment options.