Validation of the growth hormone (GH)-dependent marker method of detecting GH abuse in sport through the use of independent data sets.

CONTEXT The detection of exogenously administered growth hormone (GH) poses a formidable challenge but a detection method based on the measurement of two GH-dependent markers, IGF-I and type 3 pro-collagen (P-III-P) has been proposed. The measurement of multiple markers in conjunction with discriminant functions can improve the sensitivity and specificity of detection compared with single marker analysis. OBJECTIVE To provide further validation of the GH-dependent marker approach. DESIGN Analysis of discriminant function scores for GH detection on independent datasets. SETTING Two independent (GH-2000 and Kreischa) double blind, placebo controlled, hGH administration studies. SUBJECTS Healthy active male volunteers. INTERVENTION GH-2000 proposed a discriminant function involving IGF-I and P-III- P while the Kreischa function involved IGF-I, P-III-P and IGFBP-3. After adjustment for assay differences the formulae were applied to the other dataset. OUTCOME MEASURES Ability to detect GH use in independent datasets using a predefined specificity of approximately 1 in 10000. RESULTS The GH-2000 formula was able to detect 90% of those receiving GH in the Kreischa study at one or more time points during the study period. This sensitivity was similar to that obtained on the original GH-2000 dataset. The Kreischa formula correctly identified 41% of individuals receiving GH in the GH-2000 study. CONCLUSIONS The study provides further validation that the test proposed by GH-2000 based on IGF-I and P-III-P concentrations can be used to detect subjects receiving exogenous GH.