Beta‑Amyloid 42/40 Ratio, CSF
Use
This LC‑MS/MS assay measures beta‑amyloid 40 (AB40) as well as AB42 in cerebrospinal fluid (CSF), rather than AB42 alone. Using the ratio of beta‑amyloid 42/beta‑amyloid 40 improves sensitivity and specificity for detecting Alzheimer’s disease. Aβ42/40 ratio values ≥ 0.16 indicate low risk of Alzheimer’s disease, while values < 0.16 indicate increased risk. It is intended for clinical use in adults; not performed for individuals under 18, and pre‑test and post‑test counseling is strongly recommended.
Special Instructions
Quest Diagnostics does not perform this test for individuals under the age of 18. Pre‑test and post‑test counseling is strongly recommended.
Limitations
Not provided.
Methodology
Mass Spectrometry
Biomarkers
Result Turnaround Time
4-11 days
Related Documents
For more information, please review the documents below
Specimen
Cerebrospinal Fluid
Volume
0.5 mL
Minimum Volume
0.3 mL
Container
polypropylene tube
Collection Instructions
Collect and transport CSF in a polypropylene tube.
Storage Instructions
Store frozen.
Causes for Rejection
Hemolysis • Icterus • Lipemia • Specimen collected in glass, polystyrene, or polycarbonate tube
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 72 hours |
| Refrigerated | 5 days |
| Frozen | 31 days |