TY - JOUR VL - 13 JF - Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring N1 - © 2021 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. TI - Effects of pre-analytical procedures on blood biomarkers for Alzheimer's pathophysiology, glial activation, and neurodegeneration. Y1 - 2021/06/02/ UR - https://doi.org/10.1002/dad2.12168 ID - discovery10130389 AV - public IS - 1 KW - amyloid beta KW - biomarkers KW - blood KW - citrate KW - ethylenediaminetetraacetic acid KW - glial fibrillary acidic protein KW - lithium heparin KW - neurofilament light KW - phosphorylated tau KW - pre?analytics KW - serum N2 - Introduction: We tested how tube types (ethylenediaminetetraacetic acid [EDTA], serum, lithium heparin [LiHep], and citrate) and freeze-thaw cycles affect levels of blood biomarkers for Alzheimer's disease (AD) pathophysiology, glial activation, and neuronal injury. Methods: Amyloid beta (A?)42, A?40, phosphorylated tau181 (p-tau181), glial fibrillary acidic protein, total tau (t-tau), neurofilament light, and phosphorylated neurofilament heavy protein were measured using single molecule arrays. Results: LiHep demonstrated the highest mean value for all biomarkers. Tube types were highly correlated for most biomarkers (r > 0.95) but gave significantly different absolute concentrations. Weaker correlations between tube types were found for A?42/40 (r = 0.63-0.86) and serum t-tau (r = 0.46-0.64). Freeze-thaw cycles highly influenced levels of serum A? and t-tau (P < .0001), and minor decreases in EDTA A?40 and EDTA p-tau181 were found after freeze-thaw cycle 4 (P < .05). Discussion: The same tube type should be used in research studies on blood biomarkers. Individual concentration cut-offs are needed for each tube type in all tested biomarkers despite being highly correlated. Serum should be avoided for A?42, A?40, and t-tau. Freeze-thaw cycles > 3 should be avoided for p-tau181. A1 - Ashton, NJ A1 - Suárez-Calvet, M A1 - Karikari, TK A1 - Lantero-Rodriguez, J A1 - Snellman, A A1 - Sauer, M A1 - Simrén, J A1 - Minguillon, C A1 - Fauria, K A1 - Blennow, K A1 - Zetterberg, H ER -