Intra-individual variation of GH-dependent markers in athletes: comparison of population based and individual thresholds for detection of GH abuse in sports

J Pharm Biomed Anal. 2013 Oct;84:201-8. doi: 10.1016/j.jpba.2013.06.008. Epub 2013 Jun 20.


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.

Keywords: Biomarker; Doping; Growth hormone; Insulin-like growth factor I (IGF-I); N-terminal propeptide of type III procollagen (PIIINP); Sport.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Athletes*
  • Biomarkers / blood
  • Biomarkers / chemistry
  • Doping in Sports / prevention & control*
  • Female
  • Human Growth Hormone / blood*
  • Human Growth Hormone / chemistry*
  • Humans
  • Individuality
  • Insulin-Like Growth Factor I / chemistry
  • Male
  • Peptide Fragments / blood
  • Peptide Fragments / chemistry
  • Procollagen / blood
  • Procollagen / chemistry
  • Sports
  • Substance Abuse Detection / methods*
  • Young Adult


  • Biomarkers
  • Peptide Fragments
  • Procollagen
  • procollagen Type III-N-terminal peptide
  • Human Growth Hormone
  • Insulin-Like Growth Factor I