Markers to reduce the effect of plasma volume variance on the Athlete Biological Passport during the two-hour period after exercise

Code: T18M04NB 

The International Standard for Testing and Investigations requires that blood samples for the Athlete Biological Passport (ABP) are collected at least two hours after training or competition, in order to harmonize the passport data by reducing the impact of variation in volume of blood plasma that is induced by intensive exercise. Removal of this requirement would facilitate more frequent, convenient, cost-effective sample collection for athletes and testing authorities right after competition. A set of common clinical chemistry markers have recently been demonstrated to correct for fluctuations in plasma volume (PV) in experiments with healthy volunteers, indicating that they have potential to refine the ability of the ABP to detect blood manipulations by improving the sensitivity of the primary ABP markers. This project will evaluate the feasibility and validity of these markers in routine anti-doping settings by analyzing the markers in four WADA-accredited anti-doping laboratories. Successful validation of the PV correction method in this study will support the future implementation of this approach as a pertinent component of the ABP hematological module and enable the collection of ABP blood samples immediately after training or competition.

Main findings

Contrary to the prevailing perception, an interesting observation within this study population was that none of the hemoglobin (HGB) values exceeded the predicted ABP reference intervals 1 h post-exercise, providing evidence for a low probability of concentration-based hematological markers being affected by an exercise-induced PV shift 1 h post-physical activity in football. Regarding the PV markers examined, calculated confidence levels (based on the agreement in the magnitude and directionality of change in the PV markers values) across the entire study population were generally very low. Preliminary data processing revealed significant differences in the mean values of the results between the four laboratories, which used differing immunoassays for the analysis of PV markers. Therefore, a round of inter-laboratory comparison was added to the study design to further understand this inter-lab bias. Investigations through the ring-test confirmed, indeed, that the absolute concentrations of PV markers were dependent on the assay used, which might be one of the root causes of the observed heterogeneity in measurement. Laboratory-dependent pre-analytical conditions of samples have also been identified as a potential source of variability of PV markers measured in four different laboratories.