Endocrine Abstracts

Introduction: Chronic spontaneous urticaria (CSU) has many links to autoimmune disorders, one of a described association being with autoimmune thyroiditis. The prevalence of thyroid antibodies is as high as 50% in patients with CSU. However, the pathogenic mechanism whereby thyroid autoimmunity is link to CSU is still poorly understood.

Methods: We have analysed a case series of 20 patients with chronic urticaria and elevated TPO-antibodies, that have been presented in our departments of endocrinology and allergology within one year. After excluded all other causes of hives, patients had blood sample for thyroid antibodies and hormone levels, the eosinophil blood count, inflammatory markers, serum protein electrophoresis and immunoglobulin levels.

Results: We had 20 female patients. 11 of them (55%) were euthyroid; 4 had hypothyroidism (20%) – 3 subclinical and one overt hypothyroidism; 5 patients had hyperthyroidism (25%) – 3 subclinical and 2 patients with clinical hyperthyroidism (one with Basedow ’s Disease and one with Hashitoxicosis). We observed a biological particularity: 2 patients had associated histamine intolerance, with low level of diamine oxidase (DAO) activity, in both cases normal thyroid function.

Conclusion/Comments: The association of chronic spontaneous urticaria and autoimmune thyroiditis can hide a genetic predisposition to autoimmune diseases. It is possible that they have a common pathogenic pathway. In large studies hypothyroidism is more common than hyperthyroidism; we had more hyperthyroid patients, but just one developed Basedow’s Disease, all of the rest having a mild hyperthyroidism as an early phase of chronic autoimmune thyroiditis. There have been only a few reports on the pathophysiology of reduced DAO activity in CSU. It is known that a low activity is linked with bowel inflammation and there is an individual variability in DAO expression in epithelial cells. There has been so far no causal link between autoimmune thyroiditis and reduced DAO activity. Our 2 patients had normal thyroid function and, maybe, the links could be genetic. More studies are needed to elucidate the role of thyroid function and TPO-Abs in chronic urticaria.