Frequency of autoimmune thyroid disease in chronic urticaria.

OBJECTIVE To determine the frequency of autoimmune thyroid disease in diagnosed cases of chronic urticaria (CU) and the association between hypothyroidism and chronic urticaria if any. STUDY DESIGN Non-interventional, descriptive study. PLACE AND DURATION OF STUDY Department of Physiology, Dow University of Health Sciences, Karachi, from December 2004 to January 2006. METHODOLOGY The patients were selected from Department of Dermatology and Medical Units of Civil Hospital, Jinnah Postgraduate Medical Centre, the Aga Khan Hospital and community clinics. A total number of 60 patients were enrolled in this study. In all patients, serum antithyroid autoantibodies (antithyroglobulin and antimicrosomal/thyroperoxidase), thyroid profile (serum TSH, T3 and FT4), complete blood count, erythrocyte sedimentation rate and IgE levels were carried out. The proportions were compared using chi-square test with significance at p < 0.05. RESULTS Forty seven (78%) patients were found to have chronic urticaria (history and laboratory reports). Out of 47 patients with diagnosis of CU, elevated titres of antithyroglobulin (TGA) and antimicrosomal antibodies (TMA) were found to be present in 20 (42.6%) and 27 (57.4%) patients respectively. Serum TSH level (thyroid stimulating hormone) was increased and T3, FT4 were decreased in 20 (42.6%) patients (p < 0.001). A total number of 20 (42.5%) patients were found to be hypothyroid with chronic urticaria of greater than 6 weeks duration. CONCLUSION This study shows a statistically significant association between hypothyroidism and chronic urticaria. Full thyroid profile (serum thyroid autoantibodies, serum TSH, T3 and FT4) is highly recommended in patients with diagnosis of chronic urticaria.