Diagnosis and treatment of chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is defined as the presence of urticaria for over 6 weeks and is distinct from the inducible (physical) urticarias. Angioedema is seen in 40% of patients as well as dermatographism and delayed pressure urticaria.1 There is no exogenous stimulus, but it is strongly associated with autoimmunity. About 40% of patients have IgG antibody to the IgE receptor (or IgE, itself),2 25% have IgG antithyroid antibodies and 30% a positive ANA. As a group, mean IgE levels are elevated as is specific IgE to a host of possible autoantigens.3 When serum of patients is injected into skin (the autologous skin test), hive formation is seen (when positive) without adding antigen and reflects IgG anti-IgE receptor rather than IgE antibody. There is no diagnostic test for CSU so one has to exclude other entities.4 Figure 1 lists diagnoses (left) and tests or criteria for