Plasma level of D-dimer in patients with Chronic Idiopathic Urticaria

Abstract

Chronic urticaria is a common disorder presenting as cutaneous wheals with or without angioedema for more than 6 weeks, caused by release of vasoactive mediators from mast cells within the dermis, occurring on a continuous or recurrent basis over prolonged periods of time.

Chronic urticaria is a clinical syndrome, whereby any one of a variety of hormonal, immunological, or physical factors may be the major precipitant in a particular patient. The majority of patients have no definable underlying disease or specific physical precipitants, and can be termed 'chronic idiopathic urticaria' (CIU).

The etiology and pathogenesis of chronic idiopathic urticaria are poorly understood. However, in 30–50%of cases, autoimmune processes have been suggested as causative factors. It has been reported that mast cells may show profibrinolytic activity. The supernatants of cultured mast cells are capable of inducing the conversion of plasminogen to plasmin and of lysing a fibrin clot. Moreover, it has been demonstrated that skin mast cells may affect hemostasis by prolonging bleeding time and by inhibiting thrombin formation.

It was found that D-dimer levels are higher in patients with slight to moderate chronic idiopathic urticaria compared to normal controls and were significantly elevated in a selected group of patients with severe exacerbation of chronic idiopathic urticaria proving that the coagulation cascade is activated up to the production of fibrin as a result of the generation of thrombin. Whether the elevation of D-dimer level in CIU is a cause or a result is still debatable.

In our study, the role of D-dimer was evaluated by estimating the plasma level of D-dimer in patients with CIU and patients with CU of known cause in correlation with disease severity and treatment outcome.

Twenty patients with CIU and ten with urticaria of known cause were diagnosed by disease history, clinical picture and investigations to indicate possible causes of CU. Ten apparently healthy subjects matched for age and sex were included as controls.