Beta Amyloid 42/40 Ratio, CSF

Clinical Use

Use

To indicate the ratio of beta-amyloid 42 proteins to beta-amyloid 40 proteins measured in the CSF to aid in the assessment of disease progression in patients with suspected or probable Alzheimer's disease.

Special Instructions

Not provided.

Limitations

This test was developed and performance characteristics were determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration. Ratios less than 0.058 indicate a higher likelihood of Alzheimer's, whereas values equal to or greater indicate a lower likelihood of Alzheimer's diagnosis. The assay should be used as an adjunct to neurological evaluation, including diagnostic imaging.

Test Details

Methodology

Immunoassay (CLEIA)

Biomarkers

Beta-amyloid 40

Protein

Beta-amyloid 40

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

Beta-amyloid 42

Protein

Beta-amyloid 42

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

Beta-amyloid 42/40 Ratio

Analyte

Beta-amyloid 42/40

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

LOINC Codes

Order Codes

98584-6

Result Codes

33203-1 - AL beta42 CSF-mCnc
70072-4 - AL beta40 CSF-mCnc
98485-6 - AL beta42/ABeta 40 CSF
50398-7 - Narrative diagnostic report-Imp
75608-0 - Citation Ref Lab Test

Result Turnaround Time

5-8 days

Specimen

Cerebrospinal Fluid

Volume

8 mL

Minimum Volume

5 mL

Container

Sarstedt CSF Tube 62.610.018

Collection Instructions

Collect cerebral spinal fluid (CSF) in Sarstedt CSF Tube 62.610.018. Tube must be filled 50% to 80% minimum. Specimen must be collected in Sarstedt tube directly and cannot be transferred from a regular collection tube. If first 1 mL is hemolyzed, discard and continue to draw sample.