DBS (Capitainer-B50 and Tasso-M20) enabled detection of testosterone esters in all participants, whereas urine testing (T/E) missed cases including potential UGT2B17 del/del carriers and individuals with testosterone prescription. More AAS and steroid-esters could be detected in Capitainer-B50 versus Tasso-M20.

ABSTRACT

Dried blood spots (DBS) have emerged as a promising complement, and in some settings, an alternative, to urine for anabolic androgenic steroid (AAS) testing, offering advantages such as minimal invasiveness, simplified storage, and transportation. This study evaluated two DBS collection devices—cellulose-based Capitainer-B50 and polymer-based Tasso-M20—and compared results with traditional urine analysis. Ten self-reported AAS users were recruited and provided matched urine and DBS samples. High agreement between the two DBS devices was observed, although Capitainer-B50 showed a slightly greater detection rate, likely due to a higher sample volume (50 μL vs. 17.5 μL) improved analyte recovery, and lower background noise. Notably, DBS enabled detection of testosterone use in all 10 participants, while urine testing missed two cases with naturally low urinary testosterone/epitestosterone (T/E) ratios (most likely UGT2B17 del/del carriers). Moreover, the differentiation between prescribed and illicit use of testosterone esters was also possible in DBS, but not in urine testing, while nandrolone detection in DBS was limited at low concentrations. The findings support DBS as a sensitive and practical tool for AAS detection and provide critical advantages in detecting doping with testosterone esters in individuals with prescribed testosterone therapy and in UGT2B17 deletion carriers.