Impact of low-volume blood withdrawal on hematological biomarkers for the athlete biological passport.

This study investigated the impact of low-volume blood withdrawal on the hematological biomarkers currently considered for anti-doping purposes. After baseline measurement (D - 7), a 140 mL blood withdrawal was completed (D + 0) on 12 healthy volunteers, followed by weekly monitoring for 21 days (D + 7 - 21). Each visit consisted of a full blood count (Sysmex XN-1000) and duplicate blood volume measurements by CO-rebreathing. A significant decrease in total hemoglobin mass (Hbmass) (-2.3%, p = 0.007) and red blood cell volume (RBCV) (-2.8%, p = 0.028) was reported at D + 7. Despite no atypical passport finding (ATPF) when considering the athlete biological passport adaptive longitudinal model, hemoglobin concentration ([Hb]) increased significantly at D + 21 (+3.8%, p = 0.031). Besides, ferritin (FERR) was significantly downregulated at all points following blood withdrawal, with the largest decrease occurring at D + 7 (-26.6%, p < 0.001). Regardless of the presumable effect of blood reinfusion on ABP biomarkers, these results illustrate the challenge of monitoring hematological variables for the detection of low-volume blood withdrawal. Finally, this study outlines the sensitivity of FERR to altered erythropoiesis to support the implementation of iron markers as complementary variables for the longitudinal monitoring of blood doping, despite the potential influence of confounding factors (e.g., iron supplementations).