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HelpTest Code LAB5799 PrecivityAD2, Plasma
Additional Codes
SQ:C2AD2M
Ordering Guidance
This blood test is intended for use in patients aged 50 and older with signs or symptoms of mild cognitive impairment or dementia who are undergoing evaluation for Alzheimer disease or other forms of cognitive decline.
Shipping Instructions
1. Specimens must be shipped frozen on dry ice.
2. Place labeled aliquot tubes inside a larger tube or vial for transport.
Specimen Required
Supplies: Screw cap micro tube, 2 mL, PCR Performance Tested, Low protein-binding (T983)
Collection Container/Tube: 10 mL Purple top (K EDTA)
Submission Container/Tube: Two 2-mL screw cap micro tubes
Specimen Volume: 3 mL in 2 tubes, each containing 1.5 mL
Collection Instructions:
1. Centrifuge within two hours of collection.
2. Label two 2-mL screw-cap micro tubes.
3. Aliquot 1.5 mL of plasma into each labeled micro tube.
4. Freeze plasma (no longer than 2 hours after collection) at or below -20° C.
Secondary ID
621652Useful For
Assisting in the evaluation of adult patients, aged 50 years and older, with signs or symptoms of mild cognitive impairment or dementia who are being assessed for Alzheimer disease and other causes of cognitive decline
This is not intended for patients younger than 50 years, or for use as a screening test in patients without signs or symptoms of cognitive impairment, or for serial testing for assessment of longitudinal changes.
Method Name
Immunoprecipitation/Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name
PrecivityAD2Specimen Type
PlasmaSpecimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma | Frozen | |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
| Outside of age range Specimen collected outside of testing range (too long in storage before arrival to testing facility) Insufficient volume Incorrect labeling |
Reject |
Reference Values
Amyloid Probability Score 2 (APS2) (range of 0-100):
Negative: 0-47
Positive: 48-100
Abeta42/40 Ratio:
≥0.095 Consistent with absence of amyloid plaques
Percent p-tau217:
<4.2% consistent with absence of brain amyloid plaques
Method Description
Plasma specimens undergo immunoprecipitation followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) for the quantification of amyloid beta (Abeta) 42 and Abeta 40 peptide isoform concentrations and phosphorylated and non-phosphorylated tau at amino acid threonine, position 217 (p-tau271 and np-tau217) peptide concentrations. The percent tau phosphorylated at threonine-217 (%p-tau217) is calculated using the following equation: p-tau271/np-tau217*100. A statistical algorithm combines the Abeta42/40 and %p-tau217 to generate the Amyloid Probability Score 2 (APS2).(Meyer MR, Kirmess KM, Eastwood S, et al. Clinical validation of the PrecivityAD2 blood test: A mass spectrometry-based test with algorithm combining %p-tau217 and Abeta42/40 ratio to identify presence of brain amyloid. Alzheimers Dement.2024;20[5]:3179-3192. doi:10.1002/alz.13764)
Day(s) Performed
Monday through Friday
Report Available
13 days post sample receipt from MCLPerforming Laboratory
C2N Diagnostics LLCTest Classification
C2N Diagnostics has developed and determined the analytical and clinical validity performance characteristics of this Laboratory Developed Test (LDT). This assay has been validated pursuant to CLIA regulations and is used for clinical purposes. This assay has not been cleared or approved by the FDA.CPT Code Information
0503U
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C2AD2 | PrecivityAD2 | Not Provided |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| AD2C | Amyloid Probability Score 2 (APS2) | Not Provided |
| AD2CF | APS2 Result | Not Provided |
| AD2D | APS2 Result Interpretation | Not Provided |
| AD2E | APS2 Result Reference Interval | Not Provided |
| AD2F | APS2 Description | Not Provided |
| AD2G | Percent p-tau217 | Not Provided |
| AD2H | Percent p-tau217 Reference Interval | Not Provided |
| AD2HD | Percent p-tau217 Description | Not Provided |
| AD2I | Abeta42/40 Ratio | Not Provided |
| AD2J | Abeta42/40 Ratio Reference Interval | Not Provided |
| AD2JD | Abeta42/40 Ratio Description | Not Provided |
| AD2K | Test Description | Not Provided |
| AD2L | Limitations of Test Result | Not Provided |
| AD2M | Methods and Assay Category | Not Provided |
| AD2N | References | Not Provided |
| AD2O | Report Comment | Not Provided |
| AD2P | Performing Site | Not Provided |
Forms
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.