A-103 Analytical Performance Evaluation of Plasma NfL in a Clinical Diagnostic Laboratory
Bibliographic record
Abstract
Abstract Background Neurofilament light chain (NfL) is a neuron-specific intermediate filament that is released at a consistent low level in normal individuals and increases with age and axonal injuries. NfL is a neurodegeneration biomarker in Alzheimer’s disease (AD), multiple sclerosis, stroke, traumatic brain injury and other neurodegenerative diseases (NDD). Here, we report the analytical performance of plasma NfL using high-sensitivity methodology in a clinical diagnostic laboratory. Methods The analytical performance, encompassing precision, detection limits, interference, and linearity, was evaluated. Plasma NfL levels were measured between July and October 2023 at Neurocode USA in Bellingham, WA, using a single Lumipulse G1200 instrument following CLSI guidelines, particularly for the utilization of the Fujirebio NfL Blood RUO assay as a laboratory-developed test for clinical analysis. A total of 100 healthy control samples, near the age of AD onset, were used to validate the reference ranges. Results The average plasma NfL concentrations varied from ≤ 8.4 to ≤ 37.9 ng/L among healthy individuals aged 20 to 80 years. The Plasma NfL assay exhibits analytical measurements, including a limit of blank (LoB) of 0.75 ng/L, a limit of detection (LoD) of 1.99 ng/ml, and a limit of quantification (LoQ) of 3.96 ng/L. Its linearity ranges from 11.08 to 741.58 ng/L, with intra-laboratory precision ≤ 9% CV. Stability is maintained at 4⁰C for ≤ 72 hours, at room temperature for ≤ 4 hours, at -20⁰C for ≤ 4 weeks, and at -80⁰C for ≤ 7 days, with freeze/thaw cycles tolerated within the specified time frame. Additionally, no interference was observed at the maximum concentrations tested for bilirubin, hemoglobin, and intralipid. Conclusions With a reference range between ≤ 8.4 to ≤ 37.9 ng/L and exceptional analytical performance, the measurement of plasma NfL on a state-of-the-art instrument using CLSI guidelines, can be useful in the diagnosis and monitoring of AD and other NDD.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.009 | 0.011 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".