Influence of Demographic Factors and Sport Type on Growth Hormone-Responsive Markers in Elite Athletes

Context: GH-responsive markers of the IGF system and of collagen turnover hold promise as the basis of a GH doping test. Objective: The purpose of this study was to determine the influence of age, gender, body mass index (BMI), ethnicity, and sporting type on GH-responsive serum markers in a large cohort of elite athletes from different ethnic backgrounds. Design: The study was designed as a cross-sectional study. Participants: A total of 1103 elite athletes (699 males, 404 females), aged 22.2 ± 5.2 yr, from 12 countries and 10 major sporting categories participated in this study. Main Outcome Measures: Serum IGF-I, IGF binding protein-3 (IGFBP-3), acid labile subunit (ALS), and collagen markers [N-terminal propeptide of type I procollagen (PINP), C-terminal telopeptide of type I collagen (ICTP), N-terminal propeptide of type III procollagen (PIIINP)] were measured. Results: There was a significant negative correlation (r = −0.14 to −0.58, P < 0.0005) between age and each of the GH-responsive markers. Ser...