Autoimmune Thyroid Disease in Children with Celiac Disease

Abstract

To the Editor: We refer to the article by Ansaldi et al. (1), which presents autoimmune thyroid disease associated with celiac disease (CD) in children. According to their results, autoimmune thyroid disease was found in 90 of 343 (26.2%) patients with CD and in 20 (10%) of the control subjects (P = 0.001). We recently performed a study to evaluate the prevalence of autoimmune thyroid disease in children with CD in Eastern Turkey. Our study group consisted of 77 children with CD in whom the diagnosis was performed according to the accepted criteria of the European Society for Pediatric Gastroenterology and Nutrition (2). Of subjects included in the study, 34 (44.2%) were boys and 43 (55.8%) were girls. Mean age was 9.36 ± 4.05 years (range, 1 to 18 years). Forty healthy subjects matched for sex and age were included as a control group. CD was ruled out in these children on the basis of serological screening tests (antiendomysial antibody immunoglobulin A and antigliadin antibody immunoglobulin G). Thyroid function was assayed by measuring the levels of thyroid-stimulating hormone, free T3, free T4, thyroid microsome antibodies and antithyroglobulin antibodies. There was no serologic or clinical sign of another autoimmune disease in patients with CD except for one patient with autoimmune hepatitis. Both thyroid microsome antibodies and antithyroglobulin antibodies were positive in this patient but she was euthyroid. Hypothyroidism was observed in four (5.2%) children with CD; it was not observed in any of the controls. Medical treatment was started for all the patients with hypothyroidism. Hyperthyroidism was not observed in our patients, but it was observed in one of the control subjects (2.5%). We found that seven of 77 (9.1%) patients were positive for thyroid microsome antibodies and six of 77 (7.8%) were positive for antithyroglobulin antibodies; two of 77 showed both positive thyroid microsome antibodies and antithyroglobulin antibodies. Therefore, in 11 of 77 (14.3%), at least one antibody directed against thyroid tissue was positive. In the control group, only one patient had antithyroglobulin antibodies positivity; he was euthyroid. CD is an autoimmune disorder characterized by inflammation, villous atrophy and crypt hyperplasia of the small bowel mucosa. An association between CD and other autoimmune disorders-such as insulin-dependent diabetes, Addison's disease, systemic lupus erythematous, rheumatoid arthritis, alopecia areata and autoimmune endocrine diseases-has been described (1,3-6). Of these, autoimmune thyroid disease is commonly seen in CD (3). Collin et al. (3) reported that thyroid involvement would be evident in as many as 10% to 15% of all CD subjects and clearly more frequently than in control subjects. The growth of knowledge of the pathogenesis of CD that has taken place in recent years indicates that CD is a disease of autoimmune etiology (4). The greater frequency of thyroid disease among children with CD compared with healthy individuals justifies a routine assessment of thyroid functions. Forchielli et al. (6) and Kowalska et al. (4) reported that incidences of autoimmune thyroid disease associated with CD were 37.6%, and 41.1%, respectively. Ansaldi et al. (1) reported the frequency of CD in the largest pediatric series of CD as 26.2%. Interestingly, in the mentioned study, the reported frequency of autoimmune thyroid disease in control subjects was higher than in other studies (10%). It was not clear in the text whether the controls were tested for CD serology. This investigation is particularly important in countries where the prevalence of CD is relatively high. Hakanen et al. (5) detected autoimmune thyroid disease in patients with CD and controls as 13.9% and 2.1%, respectively. Toscano et al (7) described similar results for autoimmune thyroid disease associated with CD. In conclusion, we found the frequency of autoimmune thyroid disease associated with CD to be 14.3% in Turkish children. This result was similar to other published data. We emphasize the importance of screening selected controls for celiac serology, especially in countries where celiac prevalence is relatively high, to avoid overestimation the prevalence of thyroid disease in healthy children. Mukadder Ayşe Selimoğlu Vildan Ertekin Atatürk University, Medical Faculty Department of Pediatric Gastroenterology, Hepatology and Nutrition, Erzurum, Turkey