Insulin-like growth factor-I and mineral metabolism markers in children with idiopathic decrease in bone mass

Abstract

Objective The aim of the study was to determine whether the serum concentration of insulin-like growth factor-I (IGF-I) and its binding protein-3 (IGFBP-3) correlates with the mineral metabolism markers in children with idiopathic decrease in bone mass. Patients and methods The study comprised 62 patients aged 6–18 years, including 42 with idiopathic decrease in bone mineral density (20 with osteoporosis and 22 with osteopenia) and 20 control children. Osteoporosis and osteopenia were diagnosed on the basis of complex clinical, densitometric and biochemical examinations (in all patients secondary causes of the decreased bone mass were excluded). Serum concentration of IGF-I was determined with radioimmunoassay and IGFBP-3 using immunoradiometry. Results The children with osteoporosis and osteopenia were found to have mean IGF-I concentration statistically significantly lower than the controls (548 and 645 v. 819 ng/ml, respectively; p < 0.05). Moreover, IGF-I correlated positively with total and spinal bone mineral density. In children with osteoporosis there was also a significant relationship between IGF-I and pyridinoline and deoxypyridinoline in urine. Conclusions Lower serum IGF-I concentration together with higher bone resorption and low bone mineral density reveal involvement of this growth factor in the development of idiopathic decrease of bone mass in children.