Chronic urticaria (CU) is a common disease in which at least 50% of cases are considered to be idiopathic. 20-40% of patients with CU may have autoimmune urticaria which is defined by the presence of anti-FceRI antibodies (only one lab in the U.S. has the ability to perform the test, National Jewish in Denver, Colorado).This large study from Israel included 12,000 patients given a diagnosis of CU by either allergy or dermatology specialists during 17 years in a large health maintenance organization (HMO). Similar data were collected for 10,000 controls without CU.
Having CU was associated with an increased odds ratio for:
- hypothyroidism
- hyperthyroidism
- antithyroid antibodies
Female patients with CU had a significantly higher incidence of:
- rheumatoid arthritis
- Sjögren syndrome
- celiac disease
- type I diabetes mellitus
- systemic lupus erythematosus
These conditions were mostly diagnosed during the 10 years after the diagnosis of CU
High mean platelet volume, positive rheumatoid factor (RF), and antinuclear antibodies (ANA) were all more prevalent in patients with CU.
The authors concluded that a strong association was found between CU and major autoimmune diseases. A common pathogenic mechanism is implied by the high prevalence of autoantibodies and the existence of a chronic inflammatory process expressed by the high mean platelet volume.
These findings may have significant implications for the diagnosis and prognosis of patients with CU.
Laboratory Diagnosis of Chronic Urticaria (click to enlarge the image).
Anti-FceR1 autoantibodies in chronic autoimmune urticaria: IgG against FceRI (receptor for IgE) (click to enlarge the image).
References:
Chronic urticaria and autoimmunity: Associations found in a large population study. Confino-Cohen R, Chodick G, Shalev V, Leshno M, Kimhi O, Goldberg A. J Allergy Clin Immunol. 2012 Feb 13. [Epub ahead of print]
Image source: Urticaria, Wikipedia, public domain.