BETA-AMYLOID 42-40 Ratio, CSF

Test Code

LAB6507

Quest Code

94627X

CPT Codes
82542

Preferred Specimen

1.2 mL (0.6 mL minimum) CSF collected in a
polypropylene tube

Quest does not perform this test for individuals under
the age of 18. Pre-test and post-test counseling is
strongly recommended.

Minimum Volume

0.6 mL

Specimen Stability

Room temperature: 72 hours
Refrigerated: 5 days
Frozen: 31 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Specimen collected in a glass, polystyrene, or
polycarbonate tube

Methodology
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

Setup Schedule

Set up: Sun; Report available: 3-10 days

Report Available

3-10 days

Reference Range

See Laboratory Report

Clinical Significance

The test for CSF Beta-Amyloid by LC-MS/MS monitors both CSF beta-amyloid 40 (AB40) and 42 (AB42) endogenous peptides, rather than only AB42. The quantitation of both AB peptides permits the normalization of beta amyloid levels circulating in cerebrospinal fluid in different patients by using a ratio of beta-amyloid 42/beta-amyloid 40, resulting in an improved sensitivity for monitoring cognitive impairment that can progress to Alzheimer’s disease.

Performing Laboratory
Quest Diagnostics Nichols SJC

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.