Osteoprotegerin, Receptor Activator of Nuclear Factor Kappa B Ligand, and Growth Hormone/Insulin-Like Growth Factor-1 Axis in Children with Growth Hormone Deficiency

The growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis is involved in the regulation of the receptor activator of nuclear factor kappa B ligand (RANKL)/RANK/osteoprotegerin (OPG) system, but the exact mechanism of the associations is not fully explained. In this study we investigated the serum OPG and total sRANKL concentrations in short children who had differences in GH secretory status. We also investigated the associations between the GH/IGF-1 and OPG/RANKL systems in GH-deficient children during GH treatment. There were no significant differences in any anthropometric or biochemical parameters evaluated between the GH-deficient and GH-sufficient children. The OPG content and total alkaline phosphatase (ALP) activity increased significantly after the initiation of GH treatment, while total sRANKL remained unchanged. The variables baseline BMI SDS for height-age (β = 0.42; p < 0.05), baseline ALP activity (β = 0.36; p < 0.05), weight SDS for height-age at 6 months of GH treatment (β = 1.86; p < 0.01), and total ALP activity at 6 months of GH treatment (β = 0.48, p < 0.01) were identified as independent predictors of ΔOPG_{6-month-baseline}. We conclude that OPG and total sRANKL concentrations are independent from GH secretory status in short children. OPG elevation during GH treatment is independently associated with total ALP activity and nutritional status in GH-deficient children.