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Quest AD-Detect® Beta-Amyloid 42/40 Ratio, Plasma
Test Code11786
CPT Codes
0346U
Includes
ABeta 42
ABeta 40
ABeta 42/40 Ratio
ABeta 40
ABeta 42/40 Ratio
Preferred Specimen
1.2 mL plasma collected in a K2 EDTA (lavender-top) tube
Minimum Volume
0.6 mL
Instructions
Collect blood into a K2 EDTA Plasma tube and mix by inversion 10 times. Centrifuge to separate plasma from cells within 1 hour of collection. Carefully transfer plasma into a non-conical polypropylene tube or one of the Quest issued polypropylene (non-conical) pour-off/transfer tubes. If unable to centrifuge within 1 hour of collection, store tube on ice. Store frozen.
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: 72 hours
Frozen -20° C: 32 days
Frozen -70° C: 77 days
Refrigerated: 72 hours
Frozen -20° C: 32 days
Frozen -70° C: 77 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Moderate or gross hemolysis • Specimen collected in a glass, polystyrene, or polycarbonate tube
Methodology
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
Setup Schedule
Night
Clinical Significance
This LC-MS/MS assay measures beta-amyloid 40 (AB40) as well as AB42 in plasma, rather than AB42 alone. This permits the normalization of beta amyloid levels circulating in plasma in different patients. Using the ratio of beta-amyloid 42/beta-amyloid 40, improves sensitivity and specificity for detecting Alzheimer's disease.