RESUMO
INTRODUCTION: Pre-analytical sample handling might affect the results of Alzheimer's disease blood-based biomarkers. We empirically tested variations of common blood collection and handling procedures. METHODS: We created sample sets that address the effect of blood collection tube type, and of ethylene diamine tetraacetic acid plasma delayed centrifugation, centrifugation temperature, aliquot volume, delayed storage, and freeze-thawing. We measured amyloid beta (Aß)42 and 40 peptides with six assays, and Aß oligomerization-tendency (OAß), amyloid precursor protein (APP)699-711 , glial fibrillary acidic protein (GFAP), neurofilament light (NfL), total tau (t-tau), and phosphorylated tau181. RESULTS: Collection tube type resulted in different values of all assessed markers. Delayed plasma centrifugation and storage affected Aß and t-tau; t-tau was additionally affected by centrifugation temperature. The other markers were resistant to handling variations. DISCUSSION: We constructed a standardized operating procedure for plasma handling, to facilitate introduction of blood-based biomarkers into the research and clinical settings.
