Biochemical markers of recombinant human insulin‐like growth factor‐I (rhIGF‐I)/rhIGF binding protein‐3 (rhIGFBP‐3) misuse in athletes

Insulin-like growth factor-I (IGF-I) is reportedly misused by elite athletes, either alone or with growth hormone (GH). The GH-2000 and GH-2004 research groups previously developed a method for detecting GH misuse based on the GH-sensitive markers IGF-I and procollagen type III amino-terminal propeptide (P-III-NP). Both markers increase in response to rhIGF-I/rhIGF binding protein-3 (rhIGFBP-3) administration in recreational athletes. The aim of this pilot study was to assess the effect of rhIGF-I/rhIGFBP-3 administration on other serum markers of the GH-IGF axis and on other bone and collagen markers. Twenty-six female and 30 male recreational athletes were randomized to 28 days’ treatment with placebo or rhIGF-I/rhIGFBP-3 complex, followed by 56 days’ washout. GH-IGF axis markers (IGFBP-2, IGFBP-3, acid-labile subunit (ALS) and IGF-II) and bone and collagen markers (procollagen type I carboxy-terminal propeptide (PICP), type I collagen cross-linked carboxy-terminal telopeptide (ICTP) and osteocalcin) were measured using commercial immunoassays. In women in the high dose treatment group, mean IGF-II decreased by 53% (P=0.0028) on Day 21. Mean IGFBP-2 increased by 119% (P=0.0039) and mean ALS decreased by 40% (P=0.0022) on Day 21. There were no significant changes in IGFBP-3, osteocalcin, ICTP or PICP. In men in the high dose group, mean IGF-II decreased by 51% on Day 21 (P<0.0001). Mean IGFBP-2 increased by 125% on Day 21 (P=0.0003). There were no significant changes in IGFBP-3, ALS, osteocalcin, ICTP or PICP. Serum IGFBP-2 and IGF-II may be useful markers of rhIGF-I/rhIGFBP-3 administration in both women and men while ALS may also be a useful marker in women; these markers are now undergoing further evaluation. Copyright © 2013 John Wiley & Sons, Ltd.