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Alzheimer's Disease Markers, CSF
Ordering Recommendation
Use to evaluate for Alzheimer's disease (AD) and other causes of cognitive impairment in adults aged 55 years or older with cognitive impairment.
New York DOH Approval Status
Specimen Required
CSF
Tube type:
Preferred: 2.5 ml low-bind polypropylene false bottom CSF tube (Sarstedt, 63.614.625), available in orderable collection kit, ARUP Supply # 58810.
Acceptable: Sarstedt 72.703.600 (1.5 ml) or Sarstedt 72.694.600 (2 ml) low-bind screw cap polypropylene microtube.
Unacceptable: Standard CSF polystyrene collection tubes are not acceptable as exposing CSF to polystyrene tubes may decrease Abeta42 concentrations.
Collection instructions:
1. Perform lumbar puncture and discard the first 1 to 2 ml of CSF
2. Using the drip method, collect CSF directly into low-bind polypropylene false bottom CSF tube (ARUP Supply #58810) available online through eSupply using ARUP Connect™ or contact ARUP Client Services at 800-522-2787. Avoid use of syringes or extension tubing. Fill tube at least 50% full.
3. Freeze and send specimen in original polypropylene collection tube (do not aliquot).
-20°C: Critical frozen
Specimen types other than those listed and hemolyzed CSF. Specimens too viscous to be aspirated by instrument.
Frozen: 8 weeks
Methodology
Quantitative Electrochemiluminescent Immunoassay (ECLIA)
Performed
Mon
Reported
1-7 days
Reference Interval
| Test Number |
Components |
Reference Interval |
|---|---|---|
| Phospho-Tau(181)/Abeta42 Ratio, CSF | <= 0.023 | |
| Total-Tau/Abeta42 Ratio, CSF | <= 0.28 |
Interpretive Data
Interpretive information: The Alzheimer's Disease Markers, CSF panel is intended for use in adult patients aged 55 years and older being evaluated for Alzheimer's disease (AD) and other causes of cognitive impairment. The pTau181/Abeta42 and tTau/Abeta42 ratios provide better concordance with amyloid positron emission tomography (PET) imaging when compared to Abeta42, pTau181, and tTau individually.
Limitations: Failure to adhere to the sample collection instructions provided in the Laboratory Test Directory may result in falsely reduced Abeta42 concentrations and therefore false elevations in the reported ratios. The ratios reported have not been established for predicting development of dementia or other neurologic conditions or for monitoring responses to therapies. Results of this test must always be interpreted in the context other clinical diagnostic evaluations and should not be used alone to establish a diagnosis of AD or other cognitive disorder.
Methodology: Roche Diagnostics Inc. electrochemiluminescence assay was used. Results obtained with different assay methods or kits may be different and cannot be used interchangeably.
| Phospho-Tau (181P) CSF/ß-Amyloid (1-42) CSF ratio | Interpretation |
|---|---|
| <= 0.023 | A negative result, defined as pTau181/Abeta42 ratio value below cutoff, is consistent with a negative amyloid positron emission tomography (PET) scan result. A negative result reduces the likelihood that a patients cognitive impairment is due to AD. |
| > 0.023 | A positive result, defined as pTau181/Abeta42 ratio value above cutoff, is consistent with a positive amyloid PET scan result. A positive result does not establish a diagnosis of AD or other cognitive disorder. |
| Total Tau CSF/ß-Amyloid (1-42) CSF ratio | Interpretation |
|---|---|
| <= 0.28 | A negative result, defined as tTau/Abeta42 ratio value below cutoff, is consistent with a negative amyloid positron emission tomography (PET) scan result. A negative result reduces the likelihood that a patients cognitive impairment is due to AD. |
| > 0.28 | A positive result, defined as tTau/Abeta42 ratio value above cutoff, is consistent with a positive amyloid PET scan result. A positive result does not establish a diagnosis of AD or other cognitive disorder. |
FDA
Note
Hotline History
Hotline History
CPT Codes
83520 x3
Components
| Component Test Code* | Component Chart Name | LOINC |
|---|---|---|
| 3017619 | Phospho-Tau(181)/Abeta42 Ratio, CSF | 97102-8 |
| 3017620 | Total-Tau/Abeta42 Ratio, CSF | 41027-4 |
