Beta Amyloid 42/40 Ratio, Plasma

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

Clinical Use

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

Not provided.

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

106941-8 - Abeta42/ABeta40 Plas LC/MS/MS
33200-7 - AL beta42 Plas-mCnc
70073-2 - AL beta40 Plas-mCnc

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.