Beta Amyloid 42/40 Ratio, Plasma

Casandra

Casandra Test Code LC90412Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 505725CPT Codes 82233, 82234

Beta Amyloid 42/40 Ratio, Plasma

Also known as: 42/40 ratio, Alzheimer's lab test, B-Amyloid

Clinical Use

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Use

The plasma A42/40 ratio is intended for use as an adjunct to diagnostic evaluations of Alzheimer's disease, including neurological and cognitive performance examinations and PET neuroimaging.

Special Instructions

The test utilizes Sysmex chemiluminescence enzyme immunoassay (CLEIA) methodology. Plasma samples collected in lavender-top (EDTA) tubes must be separated from blood via centrifugation (>1500g for 10 minutes) within 40 minutes of collection. Plasma must be transferred to Labcorp polypropylene transport tube and sealed. All samples must be transported on dry ice.

Limitations

Samples that contain fibrin, red blood cells and other insoluble objects may lead to inaccurate results. This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Test Details

Methodology

Immunoassay (CLIA)

Biomarkers

Beta-amyloid 40

Analyte

Beta-amyloid 40 • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Beta-amyloid 42

Analyte

Beta-amyloid 42 • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Beta-amyloid 42/40 Ratio

Analyte

Beta-amyloid 42/40 Ratio • Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Result Codes

33200-7
70073-2

Result Turnaround Time

5 days

Specimen

Plasma

Volume

2 mL

Minimum Volume

1 mL

Container

Lavender-top (EDTA) tube

Collection Instructions

Draw full lavender-top (EDTA) tube of blood. Separate plasma from blood via centrifugation (>1500g for 10 minutes) within 40 minutes after blood collection. Transfer plasma to Labcorp polypropylene transport tube and seal.

Storage Instructions

Plasma sample may be stored for up to 24 hours at < -10°C (standard freezer) prior to placing in dry ice for shipment, or samples may be stored in the refrigerator for up to 10 hours but then must be placed on dry ice for transport. All samples must be placed on dry ice for transport and must be maintained on dry ice or similar temperatures when reaching the local lab.

Causes for Rejection

Hemolysis; lipemia; heat-treated specimen; gross bacterial contamination; wrong tube type; not stored at proper temperature

Stability Requirements

Temperature	Period
Room Temperature	4 hours
Refrigerated	10 hours
Frozen	-10°C: 24 hours; < -60°C: 100 days

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Temperature

Period

Room Temperature

4 hours

Refrigerated

10 hours

Frozen

-10°C: 24 hours; < -60°C: 100 days