ESPE Abstracts

Background: Hashimoto's Thyroiditis (HT) is a relatively common autoimmune disorder that involves both cellular and humoral immunity, the latter characterized by the presence of antithyroid antibodies. Nevertheless, despite the large number of relevant studies, the underlying pathogenetic mechanisms still remain unclear; evidence and indications pointing to both genetic and environmental components. Genetic studies have uncovered molecular associations that include immunoregulatory and thyroid specific genes. Possible environmental triggers of the autoimmune process have included the hygienic conditions, selenium and vitamin D deficiency, drugs, stressors, smoking, alcohol, toxins and infections such as HHV-6, Yersinia and the Hepatitis C virus. Streptococcal infections are known triggers of autoimmune processes such as rheumatic fever, glomerulonephritis and CNS autoimmune disorders.

Objective: The objective of this pilot study was to examine whether an association between HT, developing during childhood and adolescence, and Streptococcal infections exists.

Subject and methods: The study group included a total of 106 children (73 females and 33 males), aged 9.9±2.9 years, initially examined for various reasons in a pediatric endocrinology setting (idiopathic short statue, early puberty, premature adrenarche, slightly elevated TSH with normal thyroid hormones in routine screening or a family history of HT). Antithyroid antibodies (antiTPO and antiTg) and Antistreptolysin O (ASO) titer, a marker of Streptococcal infection, were determined. For ASO, a titer >200 IU was characterized as positive. Appropriate statistical analysis was applied.

Results: In the group of children with a positive ASO titer, presence of positive antithyroid antibodies was observed in a significantly higher percentage of children (in 68.6 %) compared to those with a negative ASO titer (in 31.40%, P = 0.001). With respect to gender, the difference in positive antithyroid antibodies was significant only in females (P=0.002 in girls and 0.282 in boys). ASO titer was significantly increased in the positive with respect to the negative antithyroid antibodies group (P<0.001). ASO positivity was not related to age nor affected by season (cold or warm months) of specimen's collection.

Conclusions: We attempted to examine whether the range of autoimmune disorders associated with streptococcal infections includes Hashimoto's Thyroditis. A significant association of ASO positivity with the presence of antithyroid antibodies was revealed in females. Our observational data obtained from a relatively small number of children and adolescents cannot reveal whether this association is causal or the result of a common underlying immunoregulatory disorder.