Serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) in healthy Thai children and adolescents: relation to age, sex, and stage of puberty.

The authors studied the serum concentrations of insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) in 260 healthy children and adolescents (115 males, 145 females) aged 5-20 years. The subjects were divided into 12 groups according to age and sex. The serum IGF-1 and IGFBP-3 concentrations increased with age and peaked at age 13-15 years in males, and 11-13 years in females. After the peak concentration, IGF-1 and IGFBP-3 levels declined significantly in males, but were still high in females. Comparing between sexes, the concentrations of IGF-1 and IGFBP-3 were greater in females than males in all age groups. However, when subjects were divided according to the stage of puberty, the different concentrations between sexes were not significant, except for children within Tanner stage V where concentrations of IGF-1 and IGFBP-3 were significantly greater in females than males. Multiple regression analysis demonstrated the age, sex, and stage of puberty-dependent of IGF-1 concentration, and only the age and sex-dependent of IGFBP-3 concentration.