Chronic idiopathic urticaria

Chronic idiopathic urticaria is recurrent itchy wheals with daily or almost daily occurrence for at least 6 weeks, without obvious cause. Eighty to 90% of these patients have no specific external cause for their disease, which is therefore labeled "idiopathic" before. It is now recognized that as many as 30-50% of patients show evidence of autoantibodies directed against either the high-affinity IgE receptor or, less frequently, against IgE. The term "autoimmune urticaria" is used increasingly nowadays to reflect advances in knowledge about these functional autoantibodies that activate mast cells and basophils. Autologous serum skin test is a useful in vivo screening test for autoimmune urticaria, with both sensitivity and specificity about 80%. It is generally accepted that thyroid autoimunity is more prevalent in patients with chronic urticaria. However, antithyroid antibodies are not a direct causative agent in chronic urticaria. It appears more likely that antithyroid antibodies and anti-IgE receptor antibodies are associated, but just parallel, autoimmune events. The role of infections in chronic urticaria remains intriguing but unresolved. The prevalence of Helicobacter pylori infection in chronic urticaria is similar to that found in the general population. However, patients with chronic urticaria may differ in their immune response to infections or may develop infection-induced autoreactivity/ autoirnmunity. Remission or improvement of chronic urticaria after H. pylori eradication was shown is some studies. Non-sedating histamine receptor antagonists should be used as first-line agents in the treatment of these patients; however, identification of patients with autoimmune urticaria is of increasing importance because of immunotherapy. Cyclosporin, intravenous immunoglobulin or plasmapheresis has been reported to be successful in severely affected refractory patients.