Some of the actions of GH are thought to be mediated through the generation of insulin-like growth factor-I (IGF-I). There are also reports that exogenous recombinant human (rh)IGF-I is being misused by athletes either alone or in combination with GH. The use of IGF-I is also banned under the World Anti-Doping Agency (WADA) list of prohibited substances. The detection of exogenously administered rhIGF-I poses a formidable challenge, as it is identical to the endogenously produced hormone.
At present there is no specific test to detect IGF-I misuse but in principle, it should be detectable using GH and IGF-I -dependent markers.
This approach would be attractive as it may allow the doping authorities to use a single test to detect doping with either GH or IGF-I. There are several pieces of evidence to support this hypothesis. First IGF-I is one of the markers that is most GH sensitive and emerged as one of the best markers to indicate GH administration. Secondly, a number of the anabolic actions of GH are mediated by IGF-I, which is known to be an integral component of the GH axis. Limited previous studies have shown that IGF-I stimulates collagen turnover in soft tissues, ligaments and bone and thus may influence P-III-NP concentrations in blood.
The aim of the IGF-2012 project was to assess whether a marker approach can be used to detect the administration of exogenous IGF-I.