Analytic evaluation of the β-human chorionic gonadotropin assay on the Abbott IMx and Elecsys2010 for its use in doping control

Objectives:The principal objective of this study was to compare the analytical performance of the Elecsys2010 (Roche Diagnostics) system with the IMx (Abbott laboratories) system for β-hCG assay in order to assess its possible utility as a confirmation test for the quantitative measurement of β-hCG in urine for doping control purposes.Design and methods:Urine samples with spiked standard known concentrations of β-hCG and different urine samples from athletes were used in order to determine the calibration curve stability and linearity, detection limit, total, within-run and between-run precision, and method comparison for the IMx and Elecsys2010 systems for β-hCG assay, along with the stability of samples, at room temperature and at 4 °C.Results:The IMx assay was linear up to 500 IU/L, whereas the Elecsys2010 assay was linear up to 1000 IU/L. The detection limit for the IMx and Elecsys2010 systems were 0.75 IU/L and 0.25 IU/L, respectively. The total precision of the IMx and Elecsys2010 systems were ≤ 5% for β-hCG concentrations ranging from 20 to 900 IU/L and from 6.67 to 55.2 IU/L, respectively. The within-run precision tests for the IMx and Elecsys2010 systems yielded CV results of 2–3% and 3–4% respectively, while the between-run precision for the Elecsys2010 was less than 4%, whereas that of IMx was 9–16%. Regression analysis with spiked urine samples yielded the following: slope (SD) 0.7104 (0.003) and y-intercept (SD) − 0.4286 (1.397) (Sy.x = 2.328; r = 0.9999; n = 5), whereas regression analysis using the athletes' urine samples yielded the following results: slope (SD) 0.3692 (0.003) and y-intercept (SD) 0.0016 (0.003) (Sy.x = 0.0096; r = 0.9924; n = 100). Sample stability studies evidenced a nonsignificant effect at 4 °C and room temperature (25 °C) for up to 1 month.Conclusions:For doping control, the IMx and Elecys2010 may be used to screen and confirm the presence of β-hCG in urine of athletes, respectively. Additional studies are needed to verify this finding. This study also underscores the need for β-hCG assays standardization for doping control.