| Test code: | 5209 |
| Type of disorder: | Dementia |
| Disease(s) tested for: | Alzheimer's Disease |
| Special Notes: | Performing site: Quest Diagnostics Nichols Institute, San Juan Capistrano |
| Clinical Significance: | Elecsys Beta‑Amyloid (1-42) CSF II, Phospho-Tau (181P) CSF and Elecsys Total‑Tau CSF are in vitro electrochemiluminescence immunoassays for the measurement of the Beta ‑Amyloid (1-42) (Abeta42), PTau (181P) and Total‑Tau (tTau) protein concentration in cerebrospinal fluid (CSF) from adult patients aged 55 years and older being evaluated for Alzheimer's disease (AD) and other causes of cognitive impairment to generate a tTau/Abeta42 and pTau-181/Abeta42 ratios and values. A negative result, defined as tTau/Abeta42 and Phospho-Tau (181P) ratio values below cutoff or an Abeta42 value above the measuring range, are consistent with a negative amyloid positron emission tomography (PET) scan result. A negative result reduces the likelihood that a patient’s cognitive impairment is due to AD. A positive result, defined as tTau/Abeta42 and pTau181/Abeta42 ratio value above cutoff, is consistent with a positive amyloid PET scan result. A positive result does not establish a diagnosis of AD or other cognitive disorder. The tTau/Abeta42 and pTau181/Abeta42 ratio results are used as an adjunct to other clinical diagnostic evaluations. |
| Methodology: | Electrochemiluminescence |
| Reference Range: | Beta-Amyloid (1-42),CSF: Not established; tTau,CSF: Not established; pTau181,CSF: Not established; tTau-181/Abeta42 Ratio: < or = 0.28; pTau181/Abeta42 Ratio: < or = 0.023 |
The CPT codes provided 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 payer being billed.
| CPT: | 84393, 82234, 84394 |
Please label each specimen tube with two forms of patient identification. These forms of identification must also appear on the requisition form.
| Specimen Type: | Cerebrospinal Fluid (CSF) |
| Specimen Stability: | Room temperature: 5 days, Refrigerated: 14 days, Frozen: 56 days, |
| Specimen Requirements: | Preferred: 1 mL CSF (0.7 mL minimum) collected in a CSF tube 63.614.625 (Sarstedt) |
| Instructions: | Perform lumbar puncture (LP) using gravity drip collection method. Avoid the use of syringes or tubings. Perform lumbar puncture (LP) before noon. Do not use the first 2 mL of CSF for AD Biomarker measurement. Subsequently, collect at least 1.0 mL of CSF directly into the CSF tube 63.614.625 (Sarstedt) for AD biomarker measurements. (Note: The mark on the tube indicates 2.5 mL.) Collect clear (non-hemolytic) CSF in a new CSF tube. Collection of CSF for other purposes can follow thereafter, if required. Do not process the CSF sample before transport to the measuring site (i.e., no mixing/inverting, no tube transfers, no aliquoting, no freezing and normally no centrifugation) until measurement. It is strongly recommended that the sample be kept at 2 8°C during transport and storage up to the time of measurement. |
| Transport Temperature: | Refrigerated (cold packs) |
| Set-up/Analytic Time: | Set up: Monday, Wednesday, Friday, Saturday ; Report available: 2-4 Days |
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