A new blood test for Alzheimer’s disease that measures a protein called p-tau217 is a notable development in the field. Its potential as a less invasive and more accessible diagnostic tool has generated interest. The prospect of a simple blood draw to aid in diagnosing Alzheimer’s represents a shift from more burdensome procedures, prompting conversations among patients, families, and clinicians about its role in dementia care.
The P-tau217 Test Explained
The p-tau217 test identifies and quantifies a specific version of the tau protein in the bloodstream. In Alzheimer’s disease, tau proteins undergo a change called phosphorylation and form tangles inside brain cells. The “p-tau217” designation refers to tau protein that has been phosphorylated at a specific location, the 217th amino acid. Research indicates that levels of this protein in the blood are closely correlated with the buildup of both amyloid plaques and tau tangles in the brain, the two hallmark pathologies of Alzheimer’s.
Detecting these changes through a blood sample is an advance. The high accuracy of p-tau217 tests in distinguishing Alzheimer’s from other neurodegenerative diseases offers a direct way to assess the underlying pathology. This provides physicians with information for evaluating individuals with cognitive impairment.
Availability and Accessibility
The availability of p-tau217 blood tests is expanding, though they are not yet universally accessible. Currently, these tests are primarily offered as Laboratory Developed Tests (LDTs). This means they are designed, manufactured, and used within a single laboratory. Companies like C2N Diagnostics and Quest Diagnostics are among the providers offering such tests, which must be ordered by a physician.
The regulatory landscape is evolving. While several companies received “Breakthrough Device” designation from the U.S. Food and Drug Administration (FDA) to expedite review, full clearance for widespread clinical use is a gradual process. In May 2025, the FDA cleared the first test that measures a ratio of pTau217 and beta-amyloid 42 for use in adults aged 55 and older with cognitive impairment. This clearance process and reliance on specialized labs means access depends on a doctor’s awareness and available lab services.
Factors Influencing Test Cost
The cost of a p-tau217 test varies based on several factors. The most direct cost is the list price from the laboratory, which a patient might pay without insurance coverage. For example, the list price for C2N Diagnostics’ PrecivityAD2 test, which measures p-tau217 and amyloid beta ratios, is around $1,450. Other tests from different labs may have list prices ranging from $300 to $500.
Insurance coverage is a variable that is still taking shape. Currently, these tests are generally not covered by Medicare or private insurance plans, meaning patients often pay the full cost out-of-pocket. As the tests gain regulatory approval and demonstrate clinical utility, insurance reimbursement policies are expected to evolve. Some laboratories may offer financial assistance programs to help eligible patients.
Even when insurance coverage becomes more common, patients may still have out-of-pocket expenses. These can include deductibles, copayments for the office visit and the test, or coinsurance, which is a percentage of the total cost. The final amount a person pays is therefore highly dependent on their specific insurance plan, the laboratory’s list price, and any available financial aid.
Comparing Costs with Traditional Diagnostic Methods
To understand the financial implications of the p-tau217 test, it is useful to compare its price to traditional diagnostic procedures for Alzheimer’s disease. The established methods for confirming amyloid plaques in the brain are amyloid Positron Emission Tomography (PET) scans and cerebrospinal fluid (CSF) analysis. Both of these methods are more expensive and invasive than a blood test.
An amyloid PET scan is a sophisticated imaging procedure that can cost several thousand dollars, with estimates ranging from $4,000 to $5,000 or more. While effective, the high cost has limited its use, and insurance coverage can be restrictive. A CSF analysis requires a lumbar puncture, also known as a spinal tap, to collect fluid for testing. The procedure and subsequent analysis can cost over a thousand dollars and is more invasive for the patient. In this context, a blood test with a list price of several hundred to over a thousand dollars presents a more affordable initial step in the diagnostic process.