Concordance Between Capillary Dried Plasma Spot and Venous Plasma Biomarkers in Traumatic Brain Injury: An Analytical Feasibility Pilot Study

The study compared the feasibility of blood collection via fingerstick (capillary dried plasma spots) with traditional venous blood sampling in patients with traumatic brain injury. Researchers measured two brain damage biomarkers in blood: glial fibrillary acidic protein (GFAP) and neurofilament light (NfL). Although proteins from capillary samples were less stable and more variable than from venous blood, measurements of both biomarkers remained well-correlated. When researchers used the GFAP/NfL ratio as an internal normalization method, concordance between capillary and venous sampling improved. The results suggest that capillary samples are analytically feasible for measuring these biomarkers, but further formal validation and clinical testing are required before clinical use.