Biochemical markers of insulin-like growth factor-I misuse in athletes:the response of serum IGF-I, procollagen type III amino-terminal propeptide and the GH-2000 score to the administration of rhIGF-I/rhIGF binding protein-3 complex

摘要

Context: The GH-2000 and GH-2004 research groups developed a method for detecting GH misuse in athletes based on the measurement of serum IGF-I and P-III-NP. There are reports that IGF-I is also misused by athletes but currently there is no internationally recognised test designed to detect recombinant human IGF-I misuse. Objective: To examine the response of serum IGF-I, P-III-NP and the GH-2000 score to rhIGF-I/rhIGFBP-3 administration in recreational athletes. Design and Setting: Randomised, double-blind, placebo-controlled rhIGF-I/rhIGFBP-3 administration study at Southampton General Hospital, UK. Participants: 56 recreational athletes (26 women, 30 men). Intervention: Participants were randomised to treatment with low dose (30mg/day), high dose (60mg/day) rhIGF-I/rhIGFBP-3 complex or placebo for 28 days. Blood was collected throughout the drug administration and washout periods. Serum IGF-I and P-III-NP were measured using commercial immunoassays and GH-2000 scores were calculated. Results: IGF-I, P-III-NP and GH-2000 score rose in response to both low and high dose rhIGF-I/rhIGFBP-3 administration. The relative maximum response of IGF-I (approximately four-fold increase in women and men) was greater than that of P-III-NP (40-50% increase in women, 35-50% increase in men). The GH-2000 formulae, which incorporate IGF-I and P-III-NP results, detected up to 61% of women and 80% of men in the rhIGF-I/rhIGFBP-3 groups but using IGF-I concentrations alone, the sensitivity increased to 94% in both women and men during the administration period. Conclusions: The rise in P-III-NP after rhIGF-I/rhIGFBP-3 administration is small compared with that after rhGH administration. Although rhIGF-I/rhIGFBP-3 administration can be detected using the GH-2000 score method, a test based on serum IGF-I alone provides better sensitivity.