[Prevalence of chronic urticaria of autoimmune origin at the Regional Hospital Adolfo López Mateos].

Background: Chronic urticaria is a common skin disorder characterized by recurrent, transitory, itchy wheals with individual lesions lasting less than 24 hours and affecting patients for six weeks or longer. In adults it has been shown that approximately 40% of the patients with chronic urticaria have autoimmune urticaria.

Objective: To determine the prevalence of autoimmune urticaria in adults with chronic urticaria.

Patients And Method: We studied adult patients with chronic urticaria by means of autologous serum skin test (ASST), and by antinuclear and antithyroid (antityroglobulin, antiperoxidase) antibodies. We compared them with a group matched by sex and age.

Results: We included 68 patients: 34 cases (patients with chronic urticaria) and 34 controls (healthy individuals). In the cases we found high levels of TSH (p = 0.003) and positive autologous serum skin test (p = 0.04), while in the controls we observed a statistically significant difference of the levels of antithyroid antibodies (p = 0.002). The prevalence of autoantibodies (antithyroid or by autologous serum) was present in 55 and 44% of the patients with chronic urticaria.

Conclusion: Autoimmunity is one of the most common causes of chronic urticaria; it may explain the pathogenesis in half of the studied cases.