Dried Blood Spots May Improve Detection of Blood Doping

In 2019, investigations have found at least 40 blood bags, 5 cross-country skiers, 5 cyclists, and 1 physician involved in a highly sophisticated blood doping scandal (1). The findings highlight the need for improved detection of blood doping practices. Athletes use blood doping methods to increase hemoglobin mass and, thus, oxygen delivery to muscle cells to obtain an unfair advantage. Hemoglobin mass can be increased by a variety of methods, including blood transfusions (autologous or allogeneic), recombinant human erythropoietin preparations (EPO)2, or by a growing number of erythropoiesis-stimulating agents (2). Often the methods are combined or used in very small doses, called microdoses, to evade detection. Because of the wide variety of blood doping methods, an indirect method capable of detecting all forms of blood doping was developed. The method measures 2 blood parameters—hemoglobin concentration [Hb] and reticulocyte percentage (Ret%)—and the OFF score, which is defined as [Hb] −60 × √Ret% (3). Any method that stimulates erythropoiesis will cause a significant increase in immature red blood cells, called reticulocytes, as well as an increase in [Hb]. Blood withdrawal, before autologous transfusion, also stimulates erythropoiesis and will increase Ret%. Additionally, negative feedback mechanisms cause a prolonged suppression of Ret% after blood transfusion or upon cessation of EPO injections, which can last for up to 3 weeks (4–6). In 2009, the World Anti-Doping Agency (WADA) implemented longitudinal measurement of the 2 blood parameters as part of the hematological module of the athlete biological passport (ABP) program. In the ABP program, an athlete's blood parameters are measured by any antidoping laboratory and entered into a database that contains the previous blood data for that athlete. The ABP program uses individual baseline variation with a Bayesian statistical model to predict normal limits for each parameter with a 99.9% probability threshold …