الفهرس 
Chronic urticariaOnly 14 pages are availabe for public view
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Abstract
Chronic urticaria (CU) is a common disorder presenting as cutaneous wheals with or without angioedema for more than 6 weeks. Chronic spontaneous urticaria (CSU) is a subtype of chronic urticaria in which the wheals are not triggered by eliciting factors.
The pathogenesis of CU is poorly understood. Several factors have been implicated, including emotional disorders, food allergy, and chronic Helicobacter pylori infections. Autoimmune processes have been suggested as causative factors in 30-50% of cases.
Evidence has accumulated for the possible involvement of the coagulation cascade in the pathogenesis of CSU. Recent studies have shown that increased thrombin generation occurs in CSU, and is directly related to the severity of the disease. Increased thrombin generation appears to be due to the activation of the extrinsic pathway of coagulation, and is followed by enhanced fibrinolysis, leading to increased plasma levels of D-dimer in these patients.
In the present study, we assessed the elevations in plasma levels of D-dimer and activated factor VII (FVIIa) in patients with CSU, and evaluated the associations of these elevations with disease severity or disease activity.
The current study was conducted on 30 patients with CSU, and 30 normal healthy individuals as controls. Patients were recruited from the Allergy and Dermatology outpatient clinics at Ain Shams University Hospitals, and were symptomatic with active chronic urticaria at the time of their enrollment. CSU was diagnosed after exclusion of all identifiable factors by investigations, which included a complete and differential blood cell count, erythrocyte sedimentation rate, skin prick test, antinuclear antibody, C3, C4, thyroid function tests, and thyroid antibodies. Plasma levels of D-dimer and FVIIa were measured for all recruited patients and controls. In addition, they were performed for CSU patients after complete disease remission.
Both groups were comparable as regards age, gender and body mass index. Severity grades among CSU patients were 1 among 5 cases (16.7%), 2 among 13 cases (43.3%), 3 among 9 cases (30%), and 4 among 3 cases (10%). Duration of disease ranged from 0.5 to 15 years, with a median (interquartile range) of 2.0 (1.0, 6.5) years.
Levels of D-dimer and FVIIa were significantly higher among cases with active CSU than among healthy controls. D-dimer levels were significantly and positively correlated with grades of disease severity among CSU cases, and were lowest among cases with grade 1 severity and highest among cases with grade 4 severity. On the other hand, FVIIa levels did not differ significantly according to the different disease severity grades.
D-dimer levels were comparable between males and females among both study groups, with no significant difference between them. Levels of FVIIa were elevated among female cases as compared to male cases, with borderline statistical significance. Both D-dimer and FVIIa showed no significant correlations with age or body mass index among either group. D-dimer and FVIIa levels were not significantly correlated with each other among cases or controls.
Levels of D-dimer and FVIIa among cases with active CSU showed a significant dramatic reduction after remission, as compared to their levels at baseline. D-dimer and FVIIa levels among cases after remission were significantly higher than levels among healthy controls.
We conclude that activation of coagulation and fibrinolysis occurs in patients with chronic spontaneous urticaria, and is related to both the severity and activity of the disease. Enhancement of the coagulation cascade in chronic spontaneous urticaria appears to be due to the activation of the extrinsic pathway of coagulation. Future studies should focus on assessing the activation of the coagulation and fibrinolytic pathways in other types of urticaria, as well as on conducting controlled clinical trials with anticoagulants in patients with severe chronic urticaria refractory to medical treatment.