The use of growth hormone (GH)‐dependent markers in the detection of GH abuse in sport: Physiological intra‐individual variation of IGF‐I, type 3 pro‐collagen (P‐III‐P) and the GH‐2000 detection score

Abstract

Summary Background Growth Hormone is abused by athletes for its lipolytic and anabolic properties. Its use is prohibited by the World Anti‐Doping Agency. The GH‐2000 project developed a methodology to detect its abuse using the concentrations of two GH‐dependent biomarkers, IGF‐I and type 3 procollagen (P‐III‐P). The sensitivity of this method may be improved by considering intra‐individual variability. Aim The aim of this study was to examine the intra‐individual variability of IGF‐I, P‐III‐P and the GH‐2000 score. Subjects and methods IGF‐I, P‐III‐P and GH‐2000 score were evaluated in four longitudinal studies involving 303 elite and 78 amateur athletes. Samples were collected over a period of up to 12 months from a total of 238 men and 143 women aged between 17 and 53 years (mean 24·2). Results The four studies showed good agreement with no apparent difference in within‐individual variation between amateur and elite athletes. The intra‐individual variability for IGF‐I ranged between 14–16% while the variability for P‐III‐P was 7–18%. No athlete tested positive for growth hormone during any of the studies. The overall mean intra‐individual variability of the GH‐2000 score was less than 0·6 units in all studies. Conclusions The high stability of marker levels suggests that concentrations are largely genetically determined. Adopting a test based on the concept of an athlete’s ‘passport’ or ‘profiling’ would take advantage of this and most likely increase the sensitivity of the test. These data also provide strong evidence that a positive test result for GH abuse would not occur as a result of chance variability.

Pitfalls of Insulin-like Growth Factor-I and Growth Hormone Assays

“…Indeed, individual IGF-I levels fluctuate much less compared with GH, but nevertheless, considerable intraindividual variation has been observed by several studies. [28][29][30][31][32] Similar to total GH secretion, IGF-I levels start decreasing after they peak in puberty. In adults, sex has only minor influence on IGF-I levels, but the IGF-I peak is observed slightly earlier in girls than in boys, especially when age is corrected for Tanner stage.…”

Doping control analysis at the Rio 2016 Olympic and Paralympic Games

“…Washing procedure was performed before Gamma Counter reading. [13] P-III-NP: UniQ RIA kit (Orion Diagnostic, Finland) was used according to the manufacturer's instructions. Briefly, 100 μL of serum samples, calibrators, and controls were incubated with 200 μL of tracer and 200 μL of antiserum (2 hours, water bath, 37°C).…”

“…Centrifuged (15 minutes, 2000 g, 4°C), supernatant discarded and Gamma Counter reading. [13] Insulins, IGF-I analogues, GHRF (GH-RH), synacthen Urine (5 mL) was subjected to SPE with an Oasis cartridge (60 mg, Waters Co., USA) after preconditioning. Elution with CH CN/H 2 O and evaporation in a vacuum centrifuge.…”

“…The XXXI Summer Olympic Games (August [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]2016) and the XV Paralympic Games (September 7-18, 2016) were held in Rio de Janeiro, marking the first time that these events were organised in South America. Doping control analyses have been conducted in Brazil since 1989, were incorporated into the International Olympic Committee (IOC) accreditation in 2002, and were absorbed by the World Anti-Doping Agency (WADA) accreditation system in 2005.…”

The development of decision limits for the implementation of the GH-2000 detection methodology using current commercial insulin-like growth factor-I and amino-terminal pro-peptide of type III collagen assays

“…These scores have not been standardised to have mean 0 and SD 1 (as in the previous GH-2000 [1] and GH-2004 publications [9][10][11][12][13]), and therefore the original proposed decision limit of 3.72 is no longer relevant.…”