582 Chronic Urticaria Associated with Thyroid Disease

BACKGROUND: Chronic urticaria has an incidence of 15% in the general population and sometimes is associated with chronic diseases such as rheumatoid arthritis, vitiligo and thyroid disorders. Chronic urticarial is characterized by wheals lasting more than 6 weeks, with alterations of the upper layers of the skin only. On histopathology there is a perivascular infiltrate characterized by T CD4 and CD8 lymphocytes and other inflammatory cells. Cytokines produced by lymphocytes, mast cells and other cells increase the expression of vascular adhesion molecules. Other mediators such as histamine increase vascular permeability causing edema, clinically represented by wheals. Treatment of chronic urticaria includes first and second generation antihistamines as first line treatment. Sometimes there is a poor response to there drugs and second line treatments such as immunosupressors are indicated. A search for systemic disorders is helpful to identify associated pathology which makes chronic urticaria reluctant to therapy. METHODS: We performed a retrospective study considering patients with chronic urticaria attending our clinic during the last 5 years. Three hundred patients with urticaria were considered, with 16% (50 patients) with a chronic disease. Six patients with chronic urticaria were associated with thyroid disease. RESULTS: We considered 6 patients with chronic urticaria with altered thyroid function tests; 4 with subclinical hypothyroidism and 2 with subclinical hyperthyroidism. All of them had a poor response to antihistamines. When a thyroid disorder was identified, they received appropriate treatment achieving control of chronic urticaria. Treatment with antihistamines was continued. CONCLUSIONS: Chronic urticaria is a disease often associated with systemic disorders including thyroid disease. We found an association with thyroid pathology in 2% of patients with chronic urticaria, with remission of cutaneous symptoms after treatment of endocrinologic disorder. No patient had clinical manifestation of thyroid disease so it is important to perform thyroid function tests to patients with chronic urticaria since identification of these disorders and appropriate treatment helps to control cutaneous symptoms.