AD-Detect® ABeta 42/40, p-tau217, and ApoE Evaluation, Plasma
- Laboratory
- Quest Diagnostics
- Test code
- 16493
- Specimen
- Plasma
- Fasting
- Not stated
- LOINC
- 104166-4, 104663-0, 106941-8, 33200-7, 70073-2
Laboratory assay overview
This test combines ABeta 42/40 ratio, p-tau217 levels, and APOE4 allele count to report out the likelihood that a patient suspected of Alzheimer's disease (AD) has a high, indeterminate, or low likelihood of amyloid pathology consistent with AD as valuated with amyloid PET. Independent measurement and interpretation of plasma amyloid ratios (ABeta 42/40), phosphorylated tau 217 (p-tau217), and APOE status provide clinically valuable insight into patient risk for development of Alzheimer's disease. Combining these core markers for AD pathology into a single analytical interpretation has been shown to significantly improve predictive performance and accuracy in assessing amyloid PET positivity and confirming pathology consistent with a diagnosis of Alzheimer's disease. [1] AD-Detect® ABeta 42/40, p-tau217, and ApoE Evaluation, Plasma is intended for patients with cognitive impairment in the age range of 50-85. This panel meets established performance criteria for confirming a diagnosis of Alzheimer's disease utilizing plasma biomarkers. [1,2] The results of this test should be interpreted in the context of pertinent clinical, family history, physical examination, and image findings. References 1. Weber D, et al. Neurol Clin Pract. 2025; 15(6):e200546. doi:10.1212/CPJ.0000000000200546 2. Palmqvist S, et al. Alzheimers Dement. 2025; 21(7):e70535. doi: 10.1002/alz.70535
Quest Diagnostics population reference ranges
Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.
| Population | Range |
|---|---|
| ABeta 42 | Not Established |
| ABeta 40 | Not Established |
| ABeta 42/40 Ratio | ≥0.170 |
| AD Detect ptau217, Plasma | ≤0.15 pg/mL |
| AD Detect® ApoE Isoform, Plasma | Not Established |
| AD Detect® Likelihood Score w/ApoE | not stated |
| Likelihood of amyloid PET positivity | not stated |
| Low Likelihood | <0.3714 |
| Indeterminate | 0.3714 to 0.5375 |
| High Likelihood | >0.5375 |
View complete laboratory reference notes
ABeta 42 | Not Established ABeta 40 | Not Established ABeta 42/40 Ratio | ≥0.170 AD Detect ptau217, Plasma | ≤0.15 pg/mL AD Detect® ApoE Isoform, Plasma | Not Established AD Detect® Likelihood Score w/ApoE Likelihood of amyloid PET positivity Low Likelihood | <0.3714 Indeterminate | 0.3714 to 0.5375 High Likelihood | >0.5375
Quest Diagnostics test directory, test code 16493