Analytic evaluation of the beta-human chorionic gonadotropin assay on the Abbott IMx and Elecsys2010 for its use in doping control.
OBJECTIVE
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 beta-hCG assay in order to assess its possible utility as a confirmation test for the quantitative measurement of beta-hCG in urine for doping control purposes.


METHODS
Urine samples with spiked standard known concentrations of beta-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 beta-hCG assay, along with the stability of samples, at room temperature and at 4 degrees 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 <or=5% for beta-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 degrees C and room temperature (25 degrees C) for up to 1 month.


CONCLUSIONS
For doping control, the IMx and Elecys2010 may be used to screen and confirm the presence of beta-hCG in urine of athletes, respectively. Additional studies are needed to verify this finding. This study also underscores the need for beta-hCG assays standardization for doping control.
Shahzad
Khurram
K
Bioanalysis and Biotransformation Center, Korea Institute of Science and Technology, 130-650, Hawolgokdong 39-1, Seoul, Korea.
Kim
Dong-Hyun
DH
Kang
Min-Jung
MJ
D002138:Calibration; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000592:standards / Q000652:urine*; D019963:Clinical Chemistry Tests / Q000295:instrumentation* / Q000379:methods; D004300:Doping in Sports / Q000517:prevention & control*; D006801:Humans; D012015:Reference Standards; D012044:Regression Analysis; D015203:Reproducibility of Results
D018997:Chorionic Gonadotropin, beta Subunit, Human