A child presents with recurrent episodes of lip and laryngeal edema and abdominal pain associated with stress levels of which of the following are reduced.
Ci esterase inhibitor Angioedema without uicaria suggests hereditary angioneurotic edema. Hereditary angioneurotic edema is caused due to deficiency of plasma protein Ci esterase inhibitor. It is an autosomal dominant disorder. It is clinically characterized by:- Episodic edema (nonpitting) in the skin and extremities as well as in the laryngeal and intestinal mucosa provoked by emotional stress or trauma or extreme changes in temperature. Pathophysiology The mediators of edema formation in these patients are proteolytic fragments of complement C2, kinin and bradykinin. - Normally these mediators are kept in check by C1 inhibitor (CIINH) Hereditary angioneurotic edema is caused due to deficiency of the enzyme C1 inhibitor (CIINH). - (CIINH) blocks the first step in the complement pathway i.e. activation of C1. C1 complement is activated by its binding to immune complex. - CIINH prevents this activation. Thus, in the absence of CIINH there is excess of activated C1 which leads to increase in the level of activated C2. - Activated C2 mediates edema formation. Besides being inhibitor of CI,CIINH is also an inhibitor of kinin ReneratinR system. -Kining generating system includes, Hageman.factor and prekallikrein. - Activated hageman factor and prekallikrein leads to the generation of bradykinin which mediates edema formation. Normally the activation of kinin generating system is prevented by (CIINH). - In the absence of (CIINH) there is increased activation of kallikrein and .factor XII which in turn leads to increased .formation of bradykinin which produces edema. Another impoant point about hereditary angioneurotic edema is :? - It presents with angioedema without uicaria. - All patients with angioedema without uicaria should be screened with C4 level which is reduced during and between the attacks of Hereditary angioneurotic edema. One more impoant point Angioneurotic edema can also be precipitated by angiotensin conveing enzyme (ACE) inhibitors, - It occurs due to increased level of bradykinin in the serum. - Bradykinin is degraded by an angiotensin conveing enzyme present in the lung. - ACE inhibitors blocks this enzyme leading to decreased degradation of Bradykinin.
C3
C5a
CI estease inhibitor
C9