Coexistence of Autoimmune Thyroiditis and Juvenile Idiopathic Arthritis.

PURPOSE: Autoimmune thyroid disease seems to occur more often in children with juvenile idiopathic arthritis (JIA) than in the general pediatric population. We investigated the prevalence of autoimmune thyroiditis (Hashimoto's thyroiditis) in young patients with JIA in Greece, which has not been evaluated previously.

METHODS: This descriptive study included patients with JIA followed up at the Pediatric Rheumatology Unit of the Second Department of Pediatrics of a tertiary general hospital in Thessaloniki, Greece. All patients were diagnosed and sorted according to the classification criteria of the International League of Associations for Rheumatology. The presence of thyroid autoantibodies was considered for determining autoimmune thyroiditis. Basic demographic, clinical, and laboratory data were collected from patients' records.  Results: The analyzed sample comprised 130 patients with JIA (mean age 12.22 years; 69.2% female). Most patients (70%) had a family history of at least one autoimmune disease and 30.8% of Hashimoto's thyroiditis. More than half (53.8%) had enthesitis-related arthritis (ERA), 22.3% had oligoarthritis, and 15.4% had psoriatic arthritis. Thyroid autoantibodies were detected in 22/130 patients (16.9%) suggesting autoimmune thyroiditis; most of these patients were euthyroid, whereas 3/22 (13.6%) had overt hypothyroidism determined by elevated levels of thyroid-stimulating hormone, decreased levels of free thyroxine, and typical ultrasound findings for Hashimoto's thyroiditis. The prevalence of clinical cases of Hashimoto's disease was 2.3%.

CONCLUSIONS: The prevalence of autoimmune thyroiditis in our JIA cohort is higher compared to the general population and consistent with the previously reported range. Hence, investigation for thyroid autoimmunity should be included in the workup of patients with JIA.