Beta-Amyloid 40 Peptide, Mass Concentration, Cerebrospinal Fluid
This test measures the amount (mass concentration) of beta-amyloid 40 peptide in cerebrospinal fluid (CSF), the fluid that surrounds the brain and spinal cord.
["It quantifies one form of beta-amyloid protein in CSF and is used mainly as a research or supportive marker when evaluating amyloid-related brain changes."]
Key facts at a glance
- LOINC
- 70072-4
- Short code
- AL beta40 CSF-mCnc
- Synonyms
- AL beta40 CSF-mCnc
- Category
- coagulation
- Sample
- csf
- Container
- Sterile tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 1-2 mL
- Stability
- Immediate analysis required, Refrigerated: 1h
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
What Is Being Measured
Beta-amyloid is a protein fragment that comes from a larger protein in the brain. Beta-amyloid 40 is one of its common forms. This test measures how much of beta-amyloid 40 is present in a sample of CSF, reported as a mass concentration (an amount per volume).
Why CSF Is Used
CSF is collected through a lumbar puncture (spinal tap). Because CSF is in direct contact with the brain and spinal cord, it can reflect proteins and other substances related to brain processes in a way that a blood sample cannot.
How the Sample Is Collected
A clinician obtains the CSF sample by lumbar puncture. The fluid is then sent to the laboratory, where it is analyzed. Because this involves a spinal tap, your care team will explain the procedure, its purpose, and what to expect.
How to Interpret Results
Results are interpreted by your clinician in the context of your symptoms, other tests, and your overall health. This test is typically reported as part of a broader panel rather than on its own, and there is no single value that applies to everyone. Discuss what your result means with the ordering provider.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Beta-amyloid 40 in CSF is studied as a marker related to amyloid protein processing in the brain. It is often measured together with other CSF markers (such as beta-amyloid 42 and tau proteins) and is used mainly in research and specialized clinical settings. It is not a stand-alone diagnostic test, and results should always be interpreted alongside clinical findings and other evaluations.
Short name
CSF Beta-Amyloid 40
Frequently asked questions
Does this test diagnose Alzheimer's disease by itself?
How is the CSF sample collected?
Will I be told a normal range?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy