Importance of cerebrospinal fluid storage conditions for the Alzheimer's disease diagnostics on an automated platform.

ABSTRACT

OBJECTIVES: Alzheimer's disease (AD) is considered the most common cause of dementia in older people. Cerebrospinal fluid (CSF) Aß1-42, Aß1-40, total Tau (t-Tau), and phospho Tau (p-Tau) are important biomarkers for the diagnosis, however, they are highly dependent on the pre-analytical conditions. Our aim was to investigate the potential influence of different storage conditions on the simultaneous quantification of these biomarkers in a fully-automated platform to accommodate easier pre-analytical conditions for laboratories. METHODS: CSF samples were obtained from 11 consecutive patients. Aß1-42, Aß1-40, p-Tau, and t-Tau were quantified using the LUMIPULSE G600II automated platform. RESULTS: Temperature and storage days significantly influenced Aß1-42 and Aß1-40 with concentrations decreasing with days spent at 4 °C. The use of the Aß1-42/Aß1-40 ratio could partly compensate it. P-Tau and t-Tau were not affected by any of the tested storage conditions. For conditions involving storage at 4 °C, a correction factor of 1.081 can be applied. Diagnostic agreement was almost perfect in all conditions. CONCLUSIONS: Cutoffs calculated in samples stored at -80 °C can be safely used in samples stored at -20 °C for 15-16 days or up to two days at RT and subsequent freezing at -80 °C. For samples stored at 4 °C, cutoffs would require applying a correction factor, allowing to work with the certainty of reaching the same clinical diagnosis.