AUTOLOGOUS SERUM SKIN TEST AND SERUM ANTITHYROID ANTIBODIES IN PATIENTS WITH CHRONIC IDIOPATHIC URTICARIA

*Dr. Sushma Chowdary Kosaraju

ABSTRACT

Background: About 25%-45% of chronic idiopathic urticaria (CIU) patients have circulating histamine releasing autoantibodies against the high affinity IgE receptor F cεR 1∝ on basophils and mast cells or, less commonly, antibodies to IgE. The term autoimmune urticaria is increasingly being accepted for this subgroup of patients. Autoimmune urticaria (AIU) has no distinctive diagnostic clinical features. Autologous serum skin test (ASST) detects AIU. Aim: To find out incidence of autoimmune urticaria among cases of CIU patients by using ASST. To find out proportion of ASST positive CIU patients with elevated thyroid autoantibodies. Methods: We conducted a prospective study in 137 CIU patients who satisfy inclusion / exclusion criteria after written informed consent. In these patients ASST, serum T3/T4/TSH levels, antithyroid antibody levels were done. Discussion: Out of 137 patients with chronic idiopathic urticaria, 63(45.9%) showed a positive reaction to the autologous serum skin test. Antithyroid antibodies were found in 46% and thyroid dysfunction in 40.5% in ASST positive patients tested. Conclusion: Our study did not show any significant difference between patients with and without antibodies regarding mean age and sex distribution, median duration of disease, simple dermographism and history of atopy. There was a trend towards correlation between ASST positivity and autoimmune thyroid disease, which needs to be confirmed with a larger study.

Keywords: Autologous serum skin test, Chronic idiopathic urticaria, Antithyroid antibodies.