Blood neurofilament light in remote settings: Alternative protocols to support sample collection in challenging pre-analytical conditions.
Introduction
This study investigated alternative pre-analytical handling of blood for neurofilament light (NfL) analysis where resources are limited.


Method
Plasma NfL was measured with single molecule array after alternative blood processing procedures: dried plasma spots (DPS), dried blood spots (DBS), and delayed 48-hour centrifugation. These were compared to standardized plasma processing (reference standard [RS]). In a discovery cohort (n = 10) and a confirmatory cohort (n = 21), whole blood was obtained from individuals with unknown clinical etiology. In the confirmatory cohort, delayed centrifugation protocol was paired with either 37°C incubation or sample shaking to test the effect of these parameters.


Results
Delayed centrifugation (R2 = 0.991) and DPS (discovery cohort, R2 = 0.954; confirmatory cohort, DPS: R2 = 0.961) methods were strongly associated with the RS. Delayed centrifugation with higher temperatures (R2 = 0.995) and shaking (R2 = 0.975) did not affect this association. DPS (P < 0.001) returned concentrations considerably lower than the RS.


Discussion
DPS or delayed centrifugation are viable pre-analytical procedures for the accurate quantification of plasma NfL.
['Simrén|Joel|J|', 'Ashton|Nicholas J|NJ|', 'Blennow|Kaj|K|', 'Zetterberg|Henrik|H|']
neurofilament light dried plasma spots dried blood spots pre‐analytical handling