Detecting EPO in Microvolumetric Capillary Serum Shipped at Ambient Temperature for Antidoping Testing

Erythropoietin receptor agonist (ERA) testing for antidoping can be achieved in both urine and blood samples. Recent published work showed the comparability between the two matrices and focused on detectability in microvolumetric capillary serum samples collected using the Tasso+ device. Currently, in the antidoping field, blood samples are required to be shipped under cold, temperature-controlled conditions. However, due to the suggested greater stability of EPO in blood compared to urine, it is believed that blood samples should be viable for ERA analysis if shipped under the ambient, not cold temperature-controlled conditions to which urine samples are subjected. In this collaborative study with the Ultimate Fighting Championship, microvolumetric capillary serum samples were collected in the field and shipped under ambient conditions to the laboratory for ERA analysis. Resulting data showed that endogenous EPO was detectable in 100% of these samples, showing no loss in detectability despite shipping under non-controlled conditions. Further, ERA analyses were conducted in the laboratory on additional in-house collected samples and post-EPO administration samples subjected to various storage and shipping conditions, also showing reliable endogenous and recombinant EPO detectability in all samples except those experiencing extreme temperature (50°C) conditions. Taken together, these data highlight the stability of EPO in blood samples and show that ERA blood samples can be collected in the field and shipped without costly temperature-controlled shipping methods and without a loss in detectability.