The Prevalence of Thyroid Autoimmunity in Children with Developmental Dyslexia

Background and Objectives. An association between developmental dyslexia and autoimmune disorders has been postulated. We aimed to evaluate the prevalence of thyroid autoimmunity in pediatric subjects with developmental dyslexia. Methods. We enrolled pediatric subjects with developmental dyslexia and, as a control group, healthy age- and sex-matched subjects without developmental dyslexia. Thyroid function was evaluated in subjects with developmental dyslexia measuring serum concentrations of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4). Thyroid autoimmunity was evaluated in all subjects measuring antithyroid peroxidase (TPO-Ab) and antithyroglobulin (TG-Ab) antibodies. In subjects with developmental dyslexia, thyroid ultrasonography (US) was also performed. Results. We enrolled 51 subjects with developmental dyslexia ( $\text{M}:\text{F}=39:12$ , mean age $12.4\pm 9$ years) and 34 controls ( $\text{M}:\text{F}=24:10$ , mean age $10.8\pm 4$ years). TPO-Ab positivity was significantly higher in subjects with developmental dyslexia compared to controls (60.8% vs. 2.9%, $p<0.001$ ), while no significant difference was found in TG-Ab positivity (16% vs. 5.8%). Thyroid US performed in 49 subjects with developmental dyslexia revealed a thyroiditis pattern in 60%. Conclusions. We found an extremely high prevalence of thyroid autoimmunity in children with developmental dyslexia. Further studies are needed to confirm our observations, but our findings may change the approach to this disorder and eventually lead to a systematic determination of thyroid autoimmunity in children with developmental dyslexia.