Beyond reasonable doubt: catching the growth hormone cheats.

There is widespread anecdotal evidence that growth hormone (GH) is used by athletes for its anabolic and lipolytic properties to improve their performance. Within adolescent athletes, GH may also be used to increase linear growth. The athletes put themselves at risk by doing so but there are also wider societal implications for this cheating. Although GH is on the World Anti-doping Agency list of banned substances, the detection of abuse with GH is challenging. Two approaches have been developed to detect GH abuse. The first is based on an assessment of the effect of exogenous GH on pituitary GH isoforms and the second is based on the measurement of markers of GH action. As a result GH abuse can be detected with reasonable sensitivity and specificity.