Capillary UCH-L1 protein blood measurement is affected by sample hemolysis

Résumé fourni par la source

OBJECTIVES: Glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) are internationally validated blood biomarkers for the management of mild traumatic brain injury (mTBI). Capillary blood sampling would facilitate point-of-care testing for dual GFAP/UCH-L1 determination, but it is more sensitive to pre-analytical variables such as hemolysis than venous blood measurements. The aim of this study was to compare capillary and venous assays and assess the impact of hemolysis on them. METHODS: Alinity system. Red blood cell hemolysate spiking experiments were performed on different analytical platforms able to measure GFAP/UCH-L1. A human albumin matrix experiment was also conducted to look for intra-erythrocytic presence of GFAP and UCHL-1. RESULTS: GFAP showed excellent correlation between capillary and venous samples (r=0.99; 95 % CI 0.98-1.0; p<0.001) with no potential clinically relevant impact on diagnostic thresholds. By contrast, UCH-L1 showed poor correlation (r=0.28; 95 % CI 0-0.57; p=0.058) and wide limits of agreement. Hemolysis caused marked overestimation of UCH-L1 using different analytical platforms, whereas GFAP remained stable. Spiking experiments confirmed that UCH-L1 overestimation was related to its presence in red blood cells. CONCLUSIONS: Capillary UCH-L1 is highly sensitive to hemolysis, limiting the reliability of its assay in capillary samples. By contrast, capillary GFAP assay displays robust analytical performance for mTBI management.

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