Technology insight: detecting growth hormone abuse in athletes.

Athletes recognized the performance-enhancing potential of human growth hormone when it became available for treatment of short stature in growth-retarded children. Although no controlled clinical studies have demonstrated a significant benefit in highly trained adults with normal pituitary function, the practice of doping increased with the introduction of recombinant human growth hormone. Evidence of widespread abuse has been gathered by police and customs authorities or provided by former athletes. It has been difficult to develop a test to prove the administration of exogenous growth hormone in athletes because of its specific physiological and biochemical properties. Significant progress has only recently been made, particularly via two differing approaches. The 'marker approach' utilizes characteristic changes in concentrations of pharmacodynamic end points of growth hormone action, for example serum concentrations of insulin-like growth factor I and factors related to bone and soft tissue turnover. The 'isoform approach' detects changes in the molecular isoform composition of circulating growth hormone evoked by the administration of exogenous recombinant growth hormone. The isoform approach was applied at the Olympic Games in Athens in 2004 and in Turin in 2006. Used in a complementary way in an out-of-competition setting, these methods are a powerful tool with which to detect growth hormone abuse in sports.