Alzheimer's Disease Evaluation Profile, CSF
- Laboratory
- Labcorp
- Test code
- 484415
- Specimen
- Csf
- Fasting
- Not stated
- LOINC
- 104134-2
- Turnaround
- 2 - 4 days
Laboratory assay overview
Elecsys β-Amyloid (1-42) CSF II assay, Elecsys Total-Tau CSF assay and Elecsys Phospho‑Tau (181P) CSF assay are in vitro electrochemiluminescence immunoassays for the measurement of the β‑Amyloid (1‑42) (Abeta42), total Tau (tTau) and Phospho‑Tau (181P) (pTau-181) protein concentrations 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 ratio value1,2 and a pTau-181/Abeta42 ratio value.1,3 The use of AD biomarkers has been included in the new consensus research diagnostic criteria for AD, MCI and preclinical AD, proposed by the National Institute on Aging (NIA) and the Alzheimer’s Association. These new criteria take into account that AD dementia is part of a continuum of clinical and biological phenomena.4,5 The new International Working Group 2 (IWG 2) criteria recommend the use of either CSF biomarker or amyloid PET imaging for evaluation of AD patients.6 In Europe, the Committee for Medicinal Products for Human Use (CHMP) published a number of positive opinions on the use of biomarkers in the context of AD for enrichment of clinical trials in pre‑clinical dementia and mild to moderate AD.7,8
View complete laboratory reference notes
β-Amyloid 1-42 (Abeta42), Total Tau (tTau) and Phospho‑Tau 181(pTau-181) are reported without reference intervals. The results from these three performed tests are used to calculate tTau/Abeta42 and the pTau-181/Abeta42 Ratios. Elecsys® tTau/Abeta42 ratio A negative result, defined as tTau/Abeta42 ratio value below cutoff or an Abeta42 value above the measuring range, is 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 ratio value above cutoff, is consistent with a positive amyloid PET scan result. Cutoff | tTau-181/Abeta42 ratio | Interpretation Cutoff (+)* | >0.28 | A positive result consistent with a positive amyloid PET scan result. Cutoff (-)† | ≤0.28 | A negative result consistent with a negative amyloid PET scan result. Invalid result for either or both Elecsys Total‑Tau CSF or Elecsys β‑Amyloid (1-42) CSFII results in tTau-181/Abeta42 ratio being reported with the abbreviation “UPTCAL,” which expands out to state: “Unable to calculate result since non-numeric result obtained for component test.” A positive result does not establish a diagnosis of AD or other cognitive disorder. The tTau-181/Abeta42 ratio result is used as an adjunct to other clinical diagnostic evaluations. Elecsys® pTau-181/Abeta42 ratio The Elecsys® pTau-181/Abeta42 ratio is highly concordant with amyloid PET and provides an alternative solution for detection of amyloid positivity.1,3 The Elecsys® pTau-181/Abeta42 ratio achieves 90% concordance with β-Amyloid PET scan results. A result above the cutoff is consistent with a positive amyloid PET visual read.1,3,9-11 The performance of the Elecsys® AD CSF ratio cutoff vs. amyloid PET visual read has been reported1,3,9 as such: pTau-181/Abeta42 ratio Cutoff (+)* | >0.023 Cutoff (-)† | ≤0.023 PPA% | 88.2 (84.4-91.2)‡ NPA% | 92.6 (89.1-95.1)‡ OPA% | 90.2(87.7-92.3)‡ • PPA: positive percent agreement • NPA: negative percent agreement • OPA: overall percent agreement *Consistent with positive amyloid PET scan result †Consistent with negative amyloid PET scan result ‡95% CI are calculated using a Wilson score method for binomial proportions Invalid result for either or both pTau-181 β‑Amyloid (1-42) results in tTau-181/Abeta42 ratio being reported with the abbreviation “UPTCAL,” which expands out to state: “Unable to calculate result since non-numeric result obtained for component test.” A negative result, defined as pTau-181/Abeta42 ratio value below cutoff or an Abeta42 value above the measuring range, is consistent with a negative amyloid positron emission tomography (PET) scan result.1,3 A negative result reduces the likelihood that a patient’s cognitive impairment is due to AD. A positive result, defined as pTau-181/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 pTau-181/Abeta42 ratio result is used as an adjunct to other clinical diagnostic evaluations.
Labcorp test directory, test code 484415