title: Intra-individual variation of GH-dependent markers in athletes: comparison of population based and individual thresholds for detection of GH abuse in sports.
abstract: The GH-2000 discriminant functions, using insulin-like growth factor I (IGF-I) and the N-terminal propeptide of type III procollagen (PIIINP), enabled the detection of growth hormone (GH) doping despite the broad inter-individual normal range of both peptides. The sensitivity of the discriminant function-based methodology may perhaps be further increased in future by applying individual athlete profiles. The purpose of the present study was to evaluate the intra-individual variability of IGF-I, PIIINP and the GH-2000 scores in athletes. For this purpose a total of eight blood samples were taken from each of fifty male and female elite athletes over a period of up to 18 months. The IGF-I and PIIINP levels, we found, lay predominantly within the reference range for elite athletes. The intra-individual variability for IGF-I ranged between 6 and 26%, while that for PIIINP ranged between 6 and 33%. The intra-individual variations of both parameters were higher in female than in male subjects and were found to be mostly moderate. We found that the intra-individual variations of the GH-2000 test scores, expressed as CV, ranged from 4 to 36% and were in most of the subjects markedly smaller than the inter-individual variation. Individual cut-offs for the GH-2000 scores would be lower than population based ones in most of the cases.
authors.affiliation: Institute of Doping Analysis and Sports Biochemistry Dresden, Dresdner Strasse 12, D-01731 Kreischa, Germany. Electronic address: astrid.kniess@idas-kreischa.de.
authors.forename: Astrid
authors.initials: A
authors.lastname: Kniess
authors.forename: Eckart
authors.initials: E
authors.lastname: Ziegler
authors.forename: Detlef
authors.initials: D
authors.lastname: Thieme
authors.forename: R Klaus
authors.initials: RK
authors.lastname: Müller
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D015415:Biomarkers / Q000097:blood / Q000737:chemistry; D004300:Doping in Sports / Q000517:prevention & control*; D005260:Female; D019382:Human Growth Hormone / Q000097:blood* / Q000737:chemistry*; D006801:Humans; D007206:Individuality; D007334:Insulin-Like Growth Factor I / Q000737:chemistry; D008297:Male; D010446:Peptide Fragments / Q000097:blood / Q000737:chemistry; D011347:Procollagen / Q000097:blood / Q000737:chemistry; D013177:Sports; D015813:Substance Abuse Detection / Q000379:methods*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; D011347:Procollagen; C041876:procollagen Type III-N-terminal peptide; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I
keywords: Biomarker; Doping; Growth hormone; Insulin-like growth factor I (IGF-I); N-terminal propeptide of type III procollagen (PIIINP); Sport