Etiological Patterns of Chronic Urticaria
Urticaria is a common dermatosis that affects about 0.5% -5% of the general population. The traditional definition of chronic urticaria is the presence of wheals for duration > 6 weeks, and it is usually assumed that hives are present most days of the week. Etiologically, urticaria is classified broadly into immunologically mediated (IgE dependent and non-IgE dependent) and non-immunologically mediated. The main effector cell is the cutaneous mast cell, which can degranulate and release mediators that are eventually responsible for wheal formation.
The disease may be related to a large set of possible causes, the first suggestion that patients with chronic urticaria and angioedema might have an autoimmune diathesis and that was supported by the observation of an increased incidence of antithyroid antibodies in such patients .ASST is considered a screening test for autoimmune urticaria. Screening of ASST positive patients for thyroid autoantibodies, ANA titer and H. pylori specific antibodies is of special importance.
It is known that urticaria may be associated with some diseases and/or triggered by some conditions characterized by sex hormone changes, including menstrual cycle, pregnancy, menopause, and hormonal contraceptives or hormone replacement therapy. However, the role of endogenous and exogenous sex hormones as well as estrogen mimetics in the disease pathogenesis is poorly understood.
Other factors include; psychophysiologic reactions, anxiety, underlying infectious diseases, food allergies, adverse reactions to food additives, cutaneous fungal infections (id reactions), and as a consequence of H. pylori infection. The diagnostic approach to urticaria is very broad and includes many clinical, chemical and serological laboratory tests.
The present study included 50 patients. Patients were investigated for CBC, ESR, ASO titers, assay of H pylori specific antibodies, stool examination, urine analysis, assessment of thyroid function status (measurement of serum levels of T3, T4 and TSH) and ANA titer. SXR was performed to detect the role of sinusitis as a cause of CU.
Our study results showed that, CU symptoms were more common in females and in middle age groups. Out of fifty patients, thirty two patients (64 %) were tested positive for ASST, while eighteen patients (36%) were negative and there was no statistically significant difference between ASST positive and ASST negative patients regarding the demographic characteristics including age, sex. Also, the clinical differences between both ASST positive and ASST negative patients did not show any statistical significance; except for associated systemic symptoms.
In our study, H. pylori antibodies were significantly higher among ASST positive patients when compared to ASST negative patients. It is postulated that H. pylori infection may induce development of pathogenic auto antibodies by molecular mimicry. Also, H. pylori antibodies showed significantly higher prevalence among patients with positive history of associated systemic symptoms when compared to patients with negative history of associated systemic symptoms.
Our results showed that ESR levels were significantly higher among patients with positive history of associated systemic symptoms, patients with positive history of associated angioedema, patients with positive history of associated systemic diseases, patients with positive history of drug intake and those with positive history of atopy when compared to those with negative histories.
In the present study abnormal urine analysis results were significantly more common among patients with positive history of drug intake, patients with positive family history of atopy and patients with positive history of associated angioedema when compared to those with negative histories. Also, results our present study showed that ASO titers were significantly higher among patients with positive history of atopy when compared to those with negative history. Also, they were showing significantly abnormal results of SXR when compared to other patients with negative history.
In conclusion, routine laboratory tests are of limited value in finding out the etiology of CU while history taking is considered the most important tool to detect the etiology. Extensive laboratory investigations, technical diagnostics, should be reserved for individual cases following a detailed history. ASST provides an easy, inexpensive investigation in CU and helps direct attention to underlying systemic auto immune diseases. Routine screening of patients with chronic urticaria with ASST might be useful in formulating therapeutic algorithms in the management of CU.
From this study, we suggested that following approach can be followed for recommended management of CU patients (Fig. 15).
Step 1:
Step 2:
Step 3:
(Treatment)
Fig.15: A proposed approach for management of CU cases |
