Beyond reasonable doubt: catching the GH cheats
There is widespread anecdotal evidence that GH has been misused by athletes for its anabolic and lipolytic properties since the early 1980s, at least a decade before GH was used therapeutically by adult endocrinologists. Since then a number of high profile athletes have admitted using GH. Despite its widespread abuse, there is debate about whether GH is ergogenic. Until recently most scientific studies have not shown a performance enhancing effect but most have employed an inappropriate design to show a benefit.
Although GH is on the World Anti-doping Agency (WADA) list of banned substances, the detection of abuse with GH is challenging. Two approaches have been developed; the first is based on the measurement of pituitary GH isoforms and was introduced at the Athens Olympic Games in 2004. The first analytical adverse finding using this test was made in February 2010 following an out-of-competition blood sample. The second approach is based on the measurement of IGF1 and N-terminal pro-peptide of type III collagen, both of which are markers of GH action. Both markers rise in a dose dependent manner and are largely unaffected by other regulators of GH secretion. When combined with gender specific discriminant function analysis, they achieve a greater sensitivity and longer window of detection than the isoform test. The development of this test is nearing completion.