Prevalence and Clinical Significance of Antithyroid Antibodies in Children with Immune Thrombocytopenic Purpura

Background and objective: To determine the prevalence and the clinical significance of thyroid autoantibodies and their influence on treatment response in children with idiopathic thrombocytopenic purpura (ITP). Patient and Method: We retrospectively analyzed the antithyroglobulin (anti-TG) and antithyroid peroxidase (anti-TPO) antibodies from the records of 151 ITP patients who were admitted to the Pediatric Hematology Department of Gaziantep University between 2009 and 2012. Results: Anti-TPO and/or anti-TG was found positive in 38 (36.8%) of 103 patients whose thyroid autoantibody levels were measured. The comparison of positivity ratios of autoantibodies between acute and chronic ITP patients showed no significant difference. However, the separate comparison of each group of ITP patients with control group showed significantly high positivity ratios of autoantibodies in ITP patients. The initial mean platelet count of anti-TPO positive patients at diagnosis was significantly less than that of the negative patients (P=.008). One month after treatment, platelet count of anti-TPO positive patients was significantly less than that of the negative patients (P=.01). Moreover, the mean platelet counts of anti-TPO positive patients were significantly less than those of the negative patients after intravenous immunoglobulin treatment (P<.001). Conclusion: We demonstrated that the thyroid-autoimmune-diseases-related autoantibodies are frequently found in childhood ITP. Although no recommendation is found in international guidelines regarding screening for thyroid autoantibodies in patients with ITP, in view of the high incidence of antithyroid antibodies and their potential negative effect on treatment response, screening these patients for such antibodies would be recommended.