Objectives There have been few studies on the association between childhood autoimmune and rheumatic diseases. Therefore, this study aims to assess the frequency of autoimmune thyroiditis (AT), coeliac disease (CD) and type I diabetes mellitus (T1DM) in children and adolescents with juvenile idiopathic arthritis (JIA) and rheumatic fever (RF). Methods This cross-sectional study includes 53 patients with JIA, 66 patients with RF and 40 healthy subjects controls. All subjects were evaluated for thyrotropin (TSH), triiodothyronine (T3), free thyroxine (FT4), antithyroglobulin (Tg) and antiperoxidase antibodies, fasting glucose, C-peptide, anti-glutamic acid decarboxylase (GAD), anti-islet cell (IA) and antitransglutaminase IgA (tTG) antibodies. Patients with thyroid dysfunction, positive anti-thyroid antibodies or tTG underwent thyroid ultrasonography and jejunal biopsy, respectively. Results In group 1 (n=53), 21 patients presented thyroid disorders (40%; 42% oligoarticular), either subclinical hypothyroidism (13%) or positive anti-thyroid antibodies (26%, 50% oligoarticular), significantly higher than in control group (p<0.009, OR=10.5, CI 1.29-85.2). In group 2 (n=66), thyroid disorders were identified in 11 patients, four (6%) with subclinical hypothyroidism and seven (11%) with positive anti-thyroid antibodies (p=0.06, compared with the control group). There were no cases of clinical overt hypothyroidism, positive anti-GAD or anti-IA, nor changes in serum C-peptide and glycemia. CD was confirmed in one patient from each group. Conclusion Patients with JIA (especially the oligoarticular form) and RF should be investigated for thyroid dysfunction. Longitudinal studies could establish screening protocols for CD in patients with JIA and RE The cost effectiveness of T1DM screening is not justified in this population.
