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 I GF 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 b asic 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 wi th 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 IG FBP-3 and plasma IGF-I concentration was determined by RIA. Pubertal d evelopment was significantly associated with IGFBP-3 and IGF-I concent rations in girls and boys, respectively (p < 0.0001, analysis of varia nce). Multivariate regression analyses between IGF-I or IGFBP-3 with a ge, 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 betw een 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 prep ubertal boys (r = 0.30, p < 0.0001). Stepwise regression analysis betw een SD score (SDS)-IGFBP-3 or SDS-IGF-I as independent variables and h eight-SDS, weigh-SDS, WFHA, and age as dependent variables, show that IGFBP3 or IGF-I are significantly correlated to WFHA only in prepubert al children. Present data suggest that interpretation of IGFBP3 concen trations during adolescence requires knowledge of gonadal steroid leve ls, and the determination of IGFBP-3 level is a useful parameter for c linical proposes mainly in prepubertal children.