In doping control laboratories, autologous blood transfusions are currently detected using an indirect method that monitors changes in an athlete's hemoglobin concentration [Hb] and reticulocyte percent (Ret%) over time. The method is limited by the need for a phlebotomist to collect venous blood and the limited blood stability which requires temperature-controlled shipment and analysis within 72 hours. These limitations significantly reduce the number of samples collected from each athlete and thus the utility of the method. We have recently developed a method to measure immature reticulocytes (IRC) and red blood cells (RBC) in dried blood spots, which could replace the current venous blood method. In the DBS method, cell-specific proteins are digested with trypsin and measured by mass spectrometry. Two proteins, CD71 and Band3, are measured to count IRC and RBC, respectively. The method was tested in an autologous transfusion study consisting of 15 subjects who received blood and 11 subjects who received saline. After transfusion, the average CD71/Band3 ratio in the blood group was statistically different from the saline group at days 5, 6, 13, and 20. The average CD71/Band3 ratio decreased to a minimum of 61 ± 8% of baseline, while Ret% decreased to 75 ± 5% of baseline. Based on experimentally defined criteria, the CD71/Band3 ratio could detect 7 out of 10 blood transfusion subjects, while Ret% could detect 3 out of 10. Thus, the DBS method could improve detection of autologous transfusion and allow increased sample collection.

Understanding and characterizing confounding factors to the Athlete Biological Passport (ABP) is crucial for the reliable interpretation of biological profiles in the antidoping field. The physiological effects on hematological parameters and plasma volume (PV) following competition in a long‐distance triathlon, as seen in the Ironman discipline, have yet to be fully described and are the focus of this study. Complete blood count blood tests were conducted on 19 Ironman triathletes before and after an Ironman triathlon to characterize changes in hematological parameters and the effect on ABP interpretation, as it was hypothesized that changes in the plasma volume may result in the presentation of atypical ABP profiles. Baseline blood samples were collected from the athletes prior to the event, and one sample was collected per day for up to 1 week following the race. Differences were observed between the male and female athletes across multiple parameters. Most importantly to the ABP, decreases in hemoglobin concentration (HGB) and hematocrit (HCT) were identified post‐race, with the largest decreases identified on day +2. The average HGB returned to pre‐race baseline levels on day +5. Beginning 5–6 days after the race, increases in the reticulocyte percentage (Ret%) were identified. Atypical Passport Findings were identified in 32% (6/19) of the ABPs, flagged mainly due to atypical hemoglobin concentration and one instance in which the OFF‐score exceeded the adaptive model limits. These results offer a characterized timeline of hematological changes and expected shifting of plasma volume following an Ironman triathlon providing important data for the reliable interpretation of ABP profiles in this field.

No abstract