SELECTED ARTICLES FROM THE RECENT LITERATURE 2005

12/15/05

Thyroid autoimmunity in chronic urticaria

Summary
Background - There has been a reported increased frequency of thyroid autoimmunity (Thy-AI) in patients with chronic idiopathic urticaria (CIU).

Findings - O'Donnell et al of St. Thomas Hospital in London, UK investigated the incidence of Thy-AI in 182 patients with CIU evaluated by them. In patients with a positive autologous serum skin test (ASST) response (n=90), serum anti-thyroid microsomal antibodies (TMA) were present in 18 individuals. In contrast, serum TMA were found in only 4 of 92 CIU patients with negative ASST.

Increased serum levels of thyroid stimulating hormone (TSH) levels were found in only 3.8% of the total CIU patient population, actually slightly less than the expected 5% incidence in the age-matched normal population. However, such increased TSH levels in CIU were seen predominantly in the ASST positive patients (13/90 vs 1/92 in the ASST negative patients).

Reference
Br J Dermatol 2005;153:331-5

Editor's Comments
Previous studies by this very experienced group and others have shown that intradermal injection of autologous serum (ASST) induces in slightly delayed onset whealing reaction in about 40-50% of patients with CIU. In most of such ASST- positive cases, the serum also induces increased in vitro histamine release from normal donor basophils. These reactions are thought to be due to antibodies directed against the alpha chain of high-affinity IgE receptor (Fc epsilon RI.

The findings described above suggest a clustering of Thyr-AI in the CIU patients with other autoimmune responses (positive ASST). The in vivo relevance of such Thy-AI is uncertain although the limited number of increased TSH levels did cluster in the ASST positive patients. Some groups have found improvement in the CIU in TMA-positive patients when treated with thyroxine.

 

<-- BACK