Serum selenium levels in children and adolescents with Hashimoto’s thyroiditis: a cross-sectional case–control study

OBJECTIVES: This study aimed to evaluate serum selenium concentrations in children and adolescents with Hashimoto's thyroiditis (HT) residing in an iodine-sufficient region and to investigate their associations with clinical, biochemical, and ultrasonographic parameters. METHODS: In this cross-sectional case-control study, 50 patients younger than 18 years diagnosed with HT and 50 age- and sex-matched healthy controls were enrolled. HT was defined by elevated anti-thyroid peroxidase and/or anti-thyroglobulin antibodies and supported by ultrasonographic findings. Serum selenium concentrations were measured using inductively coupled plasma mass spectrometry. Thyroid function tests and autoantibodies were assessed by chemiluminescent immunoassays. Statistical analyses were performed using appropriate parametric or non-parametric tests. RESULTS: The mean serum selenium concentration was significantly lower in the HT group compared with controls (64.26 ± 14.46 μg/L vs. 70.79 ± 13.55 μg/L; p=0.005). However, mean selenium levels in both groups remained within the laboratory reference range. Within the HT group, serum selenium concentrations were not significantly associated with age, sex, TSH, free T4, thyroid autoantibody titers, ultrasonographic findings, presence of goiter, or levothyroxine dose. CONCLUSIONS: Children and adolescents with HT exhibited significantly lower serum selenium concentrations compared with healthy peers. This difference reflects a relative reduction rather than overt selenium deficiency and was not associated with markers of disease activity. Larger prospective studies are warranted to clarify the clinical relevance of these findings.