Indirect biomarkers of blood doping: A systematic review

Abstract

The detection of blood doping represents a current major issue in sports and an ongoing challenge for antidoping research. Initially focusing on direct detection methods to identify a banned substance or its metabolites, the antidoping effort has been progressively complemented by indirect approaches. The longitudinal and individual monitoring of specific biomarkers aims to identify nonphysiological variations that may be related to doping practices. From this perspective, the identification of markers sensitive to erythropoiesis alteration is key in the screening of blood doping. The current Athlete Biological Passport implemented since 2009 is composed of 14 variables (including two primary markers, i.e., hemoglobin concentration and OFF score) for the hematological module to be used for indirect detection of blood doping. Nevertheless, research has continually proposed and investigated new markers sensitive to an alteration of the erythropoietic cascade and specific to blood doping. If multiple early markers have been identified (at the transcriptomic level) or developed directly in a diagnostics' kit (at a proteomic level), other target variables at the end of the erythropoietic process (linked with the red blood cell functions) may strengthen the hematological module in the future. Therefore, this review aims to provide a global systematic overview of the biomarkers considered to date in the indirect investigation of blood doping.

Establishing Personalized Blood Protein Reference Ranges Using Noninvasive Microsampling and Targeted Proteomics: Implications for Antidoping Strategies

“…Protein targets were first selected based on detectability in prior discovery-based untargeted proteomics screens, and the best-responding proteotypic peptides were selected for synthesis. Of the target proteins included in the panel, many represent potential biomarkers of blood doping by autologous blood transfer or recombinant human erythropoietin microdosing (see Supporting Information Table S5), including band 3 anion transporter (SLC4A1), carbonic anhydrase 1 (CA1), ferritin heavy chain 1 (FTH1), hemoglobin subunits (HBA1, HBB) and transferrin receptor protein 1 (TFR1). , After determining the figures of merit as well as the intra- and interassay variabilities (Figure A–F), 319 peptides corresponding to 250 proteins passed our experimental validation, as defined by experiments 1 and 2 in the CPTAC assay validation guidelines, and were used in the analysis of longitudinally profiled dried blood specimens from the study participants.…”

Annual banned‐substance review 16th edition—Analytical approaches in human sports drug testing 2022/2023

“…A consensus appears to exist in the perception that applying direct as well as biomarker‐based indirect test methods (as provided, e.g., by the ABP hematological module) enables the identification of doping practices while clearly recognizing biomarker variabilities originating from factors other than doping. However, the consensus extends also to the observation that new, complementary biomarkers would be beneficial to enhance the sensitivity of the ABP, 158–160 and intraindividual long‐term biological variation is a key factor to assess for the utility and significance of data derived from the ABP. Diaz‐Garzon et al presented results from 30 triathletes that were blood‐sampled over a period of 11 months (once monthly), and 9 hematological parameters were subjected to CV‐ANOVA to provide estimates for the respective biological variation 104 .…”