ESPE Abstracts

Chronic autoimmune thyroiditis (cAIT) and Graves’ disease (GD) is the most common autoimmune disorders in children, associated with induction of inflammation and autoimmunity process. OPG, a cytokine receptor which mediates suppressive effect on osteoclastogenesis and its soluble ligand RANKL (sRANKL) are regulators of inflammation and may be a link between bone, autoimmune disease, and vasculature.

Aim of the study: We hypothesized that cytokines OPG and sRANKL play a crucial role in modulating an immune response in both, thyroid disorders in children. Methods: We studied serum OPG and sRANKL in 22 newly diagnosed children with cAIT, 22 GD children and 20 healthy subjects with normal fT4, fT3, TSH and negative antithyroid Abs. Thyroid function (TSH, fT4, fT3), autoimmune (ATG, ATPO, TRAb) and anthropometric (weight, height, BMI, BMI-SDS, Cole index) parameters were evaluated. OPG and sRANKL concentration were measured at the beginning of disease (before treatment) by ELISA. Nonparametric statistical test and ROC analysis were performed to assess the data. Results: In our study, no significant difference was observed between sRANKL serum concentrations in studied groups (P=0.33, Kruskal-Wallis test). OPG concentrations were significantly higher (ANOVA P=0.013; Newman-Keuls P<0.01) in children with GD: (mean±SD) (4.48±2.01 pmol/L) compared to control group (3.02±1.17 pmol/L); whereas no significant difference between children with cAIT (3.79±1.28 pmol/L) vs. control group (Newman-Keuls P>0.05) and cAIT vs. GD (Newman-Keuls P>0.05) was observed. In children with hyperthyroidism we identified significant positive correlation between OPG and sRANKL (r=0.54; P<0.01) as well sRANKL and ATPO (r=0.46p P<0.05). In a cAIT group sRANKL positively correlated with thyroid hormones: fT4 (r=0.53; P<0.05) and FT3 (r=0.52; P<0.05) and negatively with TSH (r=−0.51; P<0.05). Significant positive correlation between sRANKL and the age of children (r=0.47; P<0.05) was found in a control group. ROC curve indicates good efficacy of OPG to discriminate groups of hyperthyroid and healthy children (AUC=0.716; P=0.017) at the cut-off point of 4.54 pmol/L with low sensitivity (54.5%) but high specificity (90.0%). In these groups of children, AUC of sRANKL did not differ significantly from 0.5 (P=0.458). Conclusion: Based on the performed study we suggest that OPG may be considered as a useful biochemical marker of hyperthyroidism in GD children.