Background: Cerebrospinal fluid (CSF) amyloid β1-42 (Aβ1-42), total tau (T-tau) and phosphorylated tau181 (P-tau) are finding increasing utility as biomarkers of Alzheimer’s disease (AD). The purpose of this study was to determine whether measured CSF biomarker concentrations were affected by aliquot storage volume and whether addition of detergent-containing buffer mitigates any observed effects.
Methods: AD and control CSF was distributed into polypropylene tubes in aliquots of different volumes (50–1500 μL). Aβ1-42, T-tau and P-tau were measured with and without addition of Tween 20 (0.05%).
Results: Measured concentrations of Aβ1-42 increased two-fold with aliquot storage volume. A volume increase of 10 µL caused an Aβ1-42 increase of 0.95 pg/mL [95% confidence interval (CI) 0.36–1.50, p=0.02] in controls, and 0.60 pg/mL (CI 0.23–0.98 pg/mL, p=0.003) in AD samples. Following addition of Tween 20, the positive relationship between Aβ1-42 and aliquot volume disappeared. T-tau and P-tau were not significantly affected.
Conclusions: CSF aliquot storage volume has a significant impact on the measured concentration of Aβ1-42. The introduction of a buffer detergent at the initial aliquoting stage may be an effective solution to this problem.
This work was supported by the Wolfson Foundation and the NIHR Queen Square Dementia BRU. The Dementia Research Centre in an Alzheimer’s Research UK Coordinating Centre. Gratitude is due to the laboratory staff at the Sahlgrenska University Hospital for providing the pooled CSF used in this study.
Conflict of interest statement
Authors’ conflict of interest disclosure: The authors stated that there are no conflicts of interest regarding the publication of this article.
Research funding: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
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