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Serum insulin-like growth factor-I and pro-collagen type III N-terminal peptide in adolescent elite athletes: implications for the detection of growth hormone abuse in sport.

CONTEXT
A method based on two GH-dependent markers, IGF-I and pro-collagen type III N-terminal peptide (P-III-P), has been devised to detect exogenously administered GH. Because previous studies on the detection of GH abuse involved predominantly adult athletes, the method must be validated in adolescent athletes.


OBJECTIVE
The aim of the study was to examine serum IGF-I and P-III-P concentrations in elite adolescent athletes and to determine whether the method developed in adults is appropriate to detect GH abuse in this population.


DESIGN AND SETTING
We conducted a cross-sectional observational study at national sporting organization training events.


SUBJECTS
A total of 157 (85 males, 72 females) elite athletes between 12 and 20 yr of age participated in the study.


INTERVENTION
Serum IGF-I and P-III-P were each measured by two commercially available immunoassays. GH-2000 discriminant function scores were calculated.


RESULTS
Both IGF-I and P-III-P rose to a peak during adolescence, which was earlier in girls than in boys. All GH-2000 scores lay below the proposed cutoff limit of 3.7 (although some scores were close to this value), indicating that none of these athletes would be accused of GH doping if the GH-2000 discriminant formulae were used. The results between the two immunoassays for IGF-I and P-III-P were closely aligned.


CONCLUSIONS
The GH-2000 score rises in early adolescence, reaches a peak in athletes aged 13-16 yr, and then falls. We have found no evidence that the proposed GH-2000 score developed in adults would lead to an unacceptable rate of false-positive results in adolescent athletes, but caution may be required around the time of peak growth velocity.