Serum insulin-like growth factor (IGF) binding protein-3 and IGF-I levels during childhood and adolescence. A cross-sectional study

To investigate the effect of pubertal development on serum levels of IGF binding protein-3 (IGFBP-3) and IGF-I, and the relationship between IGFBP-3 levels and height, weight, weight for height and age (WFHA), and IGF-I levels, a cross-sectional study was performed in a Spanish basic education school in Vigo (NW Spain). The study was made up of 181 girls with a mean chronologic age of 11.03 +/- 0.22 y and 173 boys with a mean chronologic age of 10.9 +/- 0.23 y. The pubertal development was graded into three groups according to estradiol and testosterone concentrations for girls and boys, respectively. All subjects were in good health and among the 5th and 95th percentile for height. Serum IGFBP-3 and plasma IGF-I concentration was determined by RIA. Pubertal development was significantly associated with IGFBP-3 and IGF-I concentrations in girls and boys, respectively (p < 0.0001, analysis of variance). Multivariate regression analyses between IGF-I or IGFBP-3 with age, sex, and estradiol or testosterone show significative correlation in prepubertal children for IGF-I (r = 0.545, p = 0.0001 and r = 0.574, p = 0.0001 for girls and boys, respectively) and only in prepubertal boys for IGFBP-3 (r = 0.336, p = 0.0012). The linear correlation between IGF-I and IGFBP-3 was significant in both prepubertal (r = 0.25, p < 0.0001) and pubertal (r = 0.40, p < 0.0001) girls, but only in prepubertal boys (r = 0.30, p < 0.0001).