Association between thyroid autoimmunity and chronic urticaria in patients versus healthy controls

Introduction
There is growing evidence that some cases of chronic idiopathic urticaria are associated with various autoimmune diseases such as thyroid autoimmunity. The association between chronic urticaria (CU) and thyroid disorders has been a subject of controversy. Some reports link CU with hyperthyroidism or hypothyroidism. The frequency of thyroid antibodies in patients with chronic idiopathic urticaria reported in 2009 was 30%, which is higher than that previously reported.
Objective
This is a case-control study that aimed to detect the presence of markers of thyroid autoimmunity (thyroid autoantibodies with or without underlying abnormal thyroid functions) among a cohort of autologous serum skin test (ASST)-positive patients with CU in comparison with ASST-negative CU patients as well as with healthy controls, and correlating it to the severity of urticaria symptoms.
Patients and methods
This study was carried out on 80 CU patients attending the Allergy and Immunology Clinic of Ain Shams University Hospitals. CU was diagnosed on the basis of the appearance of continuous recurrent hives for more than 6 weeks. The patients were subdivided into the following groups: group A - 40 CU patients with positive ASST; group B - 40 CU patients with negative ASST. In addition, 40 healthy individuals were included in this study as healthy controls. History and general examination were conducted to all study grouos. Assessment of the Urticaria Activity Score-7 and laboratory investigations including those for complete blood count, erythrocyte sedimentation rate, thyroid function, thyroid Abs, namelyantimicrosomal antibody and antithyroglobulin antibody and total immunoglobulin E (IgE), were done.
Results
Comparison between the three groups showed that antithyroglobulin antibody was highly statistically significant in group A than in both group B and healthy controls. Moreover, antimicrosomal antibody was also found to be of higher statistical significance in group A than in both group B and healthy controls. Although total IgE had no statistical significance between groups A and B, total IgE was found to be statistically significantly higher in group B than in healthy controls. Level of thyroid stimulating hormone was higher in group A than in controls, and free T3 was lower in group A than in group B.
Conclusion
We suggest that thyroid diseases have a role in CU, which was confirmed by a higher level of thyroid antibodies in the ASST-positive group than in ASST-negative patients and healthy controls.