Chronic autoimmune thyroiditis (cAIT) leads to hypothyroidism due to T cell-mediated cytotoxicity in most cases. By contrast, Graves' disease (GD) with thyrotropin receptor stimulatory autoantibodies cause hyperthyroidism. Cytokines play a crucial role in modulating immune response in both disorders. The aim of study was to evaluate the concentrations of cytokines: IL-1β, TNF-α and IL-6 in these two opposite clinical and hormonal thyroid diseases. The study group consisted of 64 children, 44 newly diagnosed, untreated children with cAIT (n = 22; with hypothyroidism) and GD (n = 22; hyperthyroidism), and the control group of 20 healthy children. Cytokine concentrations were evaluated using the ELISA technique. The studied groups of children did not differ significantly in concentrations of IL-6 (p = 0.48) and TNF-α (p = 0.067). In children with hypothyroidism, we found significantly higher concentrations of IL-1β (median 2.16 pg/ml, IQR 0.87) compared to hyperthyroidism (median 1.39 pg/l, IQR 1.27) (p < 0.01) and the control group (median 1.88 pg/ml, IQR 1.04) (p < 0.05). The results of ROC curve analysis demonstrated the usefulness of IL-1β (AUC = 0.77, p = 0.003) and TNF-α (AUC = 0.691, p = 0.034) as diagnostic parameters in cAIT which enable discrimination of children with autoimmune thyroid disease from healthy individuals. Concentrations of these markers are increased in autoimmune hypothyroidism. We found no significant sex differences in the tested parameters. In conclusion, IL-1β and TNF-α may be considered as markers of hypothyroidism, and could efficiently discriminate between healthy and autoimmune hypothyroid children. Significantly higher concentrations of IL-1β in children with hypothyroidism may be used to distinguish children with cAIT from GD patients.
Keywords: Autoimmunity; children; cytokines; serum; thyroid.