Evidence-Based Standardized Sample Handling Protocol for Blood-Based AD Biomarker Measurement

Publication Title

Evidence-based standardized sample handling protocol for accurate blood-based Alzheimer’s disease biomarker measurement: Results and consensus of the Global Biomarker Standardization Consortium

Citation

Verberk IMW, Gouda M, Antwi-Berko D, et al. Alzheimer’s & Dementia. 2025;21:e70752. doi:10.1002/alz.70752

Overview

This multi-center consensus research article reports on the development of an evidence-based, standardized pre-analytical sample handling protocol designed to improve the accuracy and reliability of blood-based biomarkers (BBMs) for Alzheimer’s disease (AD). It systematically evaluates the effects of key pre-analytical variables — including tube type, hemolysis, centrifugation settings, storage delays, and freeze–thaw cycles — on biomarker levels across multiple analytical platforms.

Background and Rationale

Blood-based biomarkers such as amyloid-β (Aβ), phosphorylated tau (p-tau) isoforms, neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) show promise in supporting AD diagnosis and disease monitoring thanks to their less invasive and more accessible nature compared with PET and cerebrospinal fluid (CSF) testing. However, variability introduced by pre-analytical handling poses a barrier to clinical implementation. Establishing standardized, evidence-backed procedures is critical to achieving biomarker measurement consistency necessary for clinical adoption and guideline development.

Key Findings

Pre-analytical effects vary widely: Biomarker measurements were significantly influenced by collection tube type, with some exceeding 10% variability.
Temperature and handling matter:Aβ peptides were especially sensitive to delays in centrifugation and storage at room temperature versus refrigerated conditions.
Stability differences among analytes: Phosphorylated tau isoforms demonstrated greater stability across pre-analytical conditions than other biomarkers, suggesting p-tau assays may be more robust to handling variation.
Implications for clinical workflows: These findings underscore the need for standardized procedures from sample collection through processing to ensure reproducible, clinically actionable BBM results.

Recommended Workflow (High-Level)

Steps for Standardized Sample Handling

Select and use validated collection tubes with defined anticoagulant properties to minimize variation in analyte stability.
Minimize delays between collection and processing; ideally process samples within a defined, short timeframe and under controlled temperatures (e.g., 2–8 °C).
Control for hemolysis and centrifugation settings to reduce artifactual changes in key biomarker concentrations.
Avoid excessive freeze–thaw cycles by aliquoting samples at initial processing to preserve biomarker integrity.
Document all pre-analytical factors to support data interpretation and cross-site harmonization.