The autologous serum skin test in the follow-up of patients with chronic urticaria.

BACKGROUND: The presence of anti-FcepsilonRI and anti-IgE autoantibodies in a subset of patients with chronic urticaria suggests their aetiopathogenetic role. In clinical practice, the presence of these antibodies is usually considered when the autologous serum skin test (ASST) is positive.

AIMS: To evaluate if the positive ASST follows up the activity of chronic urticaria.

METHODS: Autologous serum skin test and thyroid autoantibody detection were performed in 82 patients with chronic urticaria and repeated 1 year later, when the vast majority of patients were symptom-free. Twenty patients with Hashimoto thyroiditis (HT), who had never suffered from urticaria, represented the control group.

RESULTS: At the start of the study, the prevalence of positive ASST was 46.6%. The association of HT-urticaria was 29.3%. ASST was positive in 62 and 39% of patients with and without HT, respectively (P > 0.05 ns). One year later, 28 of 34 patients with a positive ASST were symptom-free, but 50% of them were positive for ASST. The ASST was positive in 86.7 and 8% of patients with and without HT, respectively (P < 0.001). In the control group, ASST was always negative.

CONCLUSIONS: The co-existence of autoimmune thyroiditis with chronic urticaria seems to induce a significant difference in the persistence of a positive ASST. Consistent with previous reports, a positive ASST correlates with disease exacerbation in chronic urticaria patients without thyroiditis. In patients with thyroiditis and urticaria, positive ASST persists even after the urticaria has disappeared, thus questioning whether a positive ASST to be a surrogate marker of the functional role of anti-FcepsilonRI and anti-IgE autoantibodies.