RESUMEN
BACKGROUND AND OBJECTIVES: Chronic idiopathic urticaria refers to recurrent hives of more than six weeks duration and in approximately 80% of cases, the etiology is unknown. Recently, involvement of an autoimmune mechanism in the pathogenesis of chronic idiopathic urticaria has been suggested. Thyroid autoimmunity has been reported in patients with chronic idiopathic urticaria and treatment with thyroxine in selected cases induced clinical remission. MATERIALS AND METHODS: We studied 99 patients with chronic idiopathic urticaria to evaluate the clinical significance of anti-thyroid auto-antibodies including anti-thyroglobulin and antimicrosomal antibodies. Thirty-four normal volunteers were selected as controls. The prevalence of these two auto-antibodies as well as laboratory findings and clinical features between these two groups were compared. RESULTS: Thyroid auto-antibodies were positive in 24% of patients compared to 8.7% of control patients and the duration of the disease was significantly longer in the patients with thyroid auto-antibodies than in those without thyroid auto-antibodies, respectively (p<0.05). There was no significant difference in age, positive rate of ANA and total eosinophil count. Administration of thyroxine to five patients with refractory urticaria resulted in improvement in three patients. CONCLUSION: Thyroid autoimmunity is associated with chronic idiopathic urticaria in some patients. Administration of thyroxine resulted in improvement of symptoms in some of these patients. Therefore, we recommend routine testing of thyroid auto-antibodies in patients with retractable chronic idiopathic urticaria.