Osteoprotegerin and C-telopeptide of type I collagen in Polish healthy children and adolescents.

PURPOSE Most metabolic bone diseases are characterized by a disturbances in bone resorption, therefore biochemical markers concerning this process are of special interest. Recently, the novel cytokine osteoprotegerin (OPG), belonging to the tumor necrosis factor receptor family has been established as an endogenous inhibitor of osteoclastogenesis and resorption process. In addition serum C-telopeptide of type I collagen (s-CTX) is one of the resorption markers released into circulation as a result of the osteoclast mediated degradation of type I collagen. However, a clinical application of OPG and s-CTX in children may be difficult by less information of suitable reference data in relation to age, race and sex. The aim of our study was to invastigate serum concentrations of both markers in polish healthy children and adolescents. MATERIAL AND METHODS We examined 102 healthy children and adolescents in 6-24 years of age, divided on prepubertal, pubertal and postpubertal groups. OPG and s-CTX were determined by ELISA kits from Biomedica (Austria) and Osteometer (Denmark) respectively. RESULTS The highest mean values of OPG were in prepubertal girls (4.64 +/- 0.57 pmol/L) and boys (4.28 +/- 0.86 pmol/L). Next, in older children and adolescents gradually decreased of OPG concentration was observed. We also obtained the decreased of s-CTX concentration in studied children except these in pubertal period. Generally, we obtained significant positive correlation between OPG and s-CTX in all observed groups (n = 102, r = 0.653; p < 0.0001). CONCLUSIONS We report the age-related decrease in circulating endogenous OPG during childhood and adolescence. Serum OPG concentration in postpubertal period may be similar to those presented in young adults. Prospective studies are needed to investigate the influence of OPG on bone metabolism in children.