Dried blood spots, an emerging tool for doping control

Abstract

The presentation will afford information on the possibilities for dried blood spot (DBS) samples as a new tool supporting the control of the abuse of prohibited substances in the world of sport. Based on previous developments in other biological fields, recent years have seen increasing studies devoted to the possible application of dried drops of blood collected on different support materials as a promising tool to detect the presence of prohibited substances in the body of potential doping athletes. Among the studied analytes, there are examples of most of the groups of substances in the extensive prohibited list of the World Antidoping Agency (WADA). In general terms, the mere presence of most of those prohibited substances in sports drug testing showed by DBS could be enough to be considered as proof of external application to the body, and therefore susceptible to plausible sanctions. However, in other cases, the decision on potential positivity should be based on quantitative criteria (the so-called threshold substances), which is somehow more challenging for DBS. Pre-analytical aspects such exact volume of blood collected in the spots, hematocrit derived effects or homogeneity of the spots may be relevant. Examples of DBS testing for some of the more representative compounds (e.g. testosterone esters, stimulants, erythropoietin, human growth hormone, GH secretagogues, …) analyzed by chromatographic, mass spectrometric, electrophoretic or immunological methods will be presented. Also, considerations related to: – different potential matrices to collect the blood spots, such as cellulose based materials or polymers supports; – collection from finger prick or upper arm; – comparison of capillary vs. venous blood; – use of either manual or device-based collecting approaches; – insight into the degree of acceptability of those different possibilities by athletes, will be commented. Given the strict requirements for procedures in doping control (e.g. WADA and ISO 17025 accreditations), other aspects such as rigorous sample collection supervision (sample A for initial analysis and sample B for counter analysis), transport, analytical procedures and storage are to be aligned with the strictness for other usual samples such as urine or liquid blood in sport drug testing. To this end, a comprehensive Technical Document is being developed by a Working Group and to be approved by the WADA. In a first step, qualitative applications are included. A second step, addressed to threshold substances requiring quantitative estimations, is to be subsequently developed. DBS appear as an emerging new tool for prohibited drugs testing in sport, initially supporting more traditional procedures in the field such as urine or liquid blood analyses, but also susceptible of further developments by itself alone. Advantages in terms of easiness of collection, greater analyte stability and simple transport and storage, probably will overcome limitations such as the reduced amount of available sample and consequent limit in the number of substances detectable from a single DBS. In any case, its emerging applicability in sports drug testing will need strict technical controls.