Chronic urticaria

Chronic urticaria remains a major problem in terms of etiology, investigati on, and management. It is important to identify patients in whom physical u rticaria is the principal cause of disability. Once confirmed by appropriat e challenge testing, no further investigation is required. Urticarial vascu litis (UV) is a major differential diagnosis of "idiopathic" urticaria (CIU ). I perform biopsy of most patients in this category because UV cannot be considered confirmed in the absence of histologic evidence. Patients with c onfirmed UV need to be thoroughly investigated for paraproteins, lupus eryt hematosus hepatitis B and C, and inflammatory bowel disease. Of patients wi th CIU, a few (<5%) prove to have food additive reactivity confirmed by pla cebo-controlled challenge testing. There is no convincing evidence of the i nvolvement of Helicobacter pylori or parasite infestation as a cause of chr onic urticaria, although H pylori could have an indirect role. Recently it has become clear that 27% to 50% of patients with CIU hare functional autoa ntibodies directed against the alpha-chain of the high-affinity IgE recepto r or less commonly against IgG. These antibodies, whose involvement has now been independently confirmed in several centers, are identified by autolog ous serum shin testing and confirmed by histamine release studies or immuno blotting. Their removal (by intravenous Ig or plasmapheresis) or treatment by cyclosporine has proved highly beneficial in severely affected patients. However, the routine treatment of all CIU patients, irrespective of etiolo gy, remains the Judicious use of H-1 antihistamines.