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Phospho-Tau 217, Plasma
Ordering Recommendation
Use to evaluate for Alzheimer’s disease and other causes of cognitive impairment in adults aged 60 years or older who present with cognitive decline. This is not a standalone test; it should be used as part of a comprehensive diagnostic workup. Refer to the Additional Technical Information document for more information.
New York DOH Approval Status
Specimen Required
Plasma (EDTA)
Transfer 1 mL plasma to an ARUP standard transport tube (Min: 0.5 mL). Separate plasma from cells within 2 hours of collection.
Frozen
Hemolyzed or icteric specimens
Room Temperature: Unacceptable
Refrigerated: 1 week
Frozen: 2 weeks
Methodology
Qualitative Chemiluminescent Immunoassay (CLIA)
Performed
Varies
Reported
1-8 days
Reference Interval
| Test Number |
Components |
Reference Interval |
||
|---|---|---|---|---|
| pTau 217 |
|
Interpretive Data
Interpretive Data
Interpretive information: The Phospho-Tau 217, Plasma test is intended for use in patients aged 60 years and older who present with cognitive impairment and who are being evaluated for Alzheimer's disease and other causes of cognitive decline. The test is reported as a qualitative result (positive, negative, or indeterminate). Assay results correlate highly with the presence or absence of amyloid deposition as measured by amyloid PET scan. In a clinical validation set of 524 participants aged 60 years and over who presented with cognitive impairment, a positive result had a sensitivity of 90%, a negative result had a specificity of 90%, and 17% of results were indeterminate.
Limitations: Plasma phospho-Tau 217 must be interpreted in conjunction with other patient clinical information. It is not intended to be used as a screening test or stand-alone diagnostic test and is not intended for therapeutic monitoring. Results obtained with different assay methods or kits cannot be used interchangeably.
| pTau 217 Result | Value | Interpretation |
|---|---|---|
| Negative | <0.13 U/mL | A test result reported as negative is consistent with absence of amyloid deposition in brain as detected by amyloid PET scan. A negative result reduces the likelihood that a patients cognitive impairment is due to Alzheimer's disease. |
| Indeterminate | >=0.13 to <0.20 U/mL | A test result reported as indeterminate indicates that amyloid plaques may or may not be present. Additional diagnostic testing, such as other laboratory testing or amyloid PET scan, should be considered based on clinical presentation. If symptomatology persists or evolves, repeat testing may be helpful. |
| Positive | >=0.20 U/mL | A test result reported as positive is consistent with the presence of amyloid deposition in brain as measured by amyloid PET scan. A positive result by itself does not establish a diagnosis of Alzheimer's disease or other cognitive disorder. |
Laboratory Developed Test (LDT)
Note
Hotline History
Hotline History
CPT Codes
84393
Components
| Component Test Code* | Component Chart Name | LOINC |
|---|---|---|
| 3019124 | pTau 217 |
Aliases
- Phosphorylated tau 217, Plasma Tau, Human Phospho-Tau Thr217
