HAE with normal C1INH levels
Î Familial recurrent angioedema characterized by normal C1INH function
might represent HAE with normal C1INH levels; however, there are no
agreed upon criteria for diagnosing HAE with normal C1INH levels at this
time (C).
Î Some kindreds with HAE with normal C1INH levels appear to require high
estrogen levels for the angioedema to manifest. (C)
Î HAE with normal C1INH levels may be caused by increased bradykinin
signaling. (C)
Î Drugs developed for patients with HAE with reduced C1INH function have
been reported to be effective in some patients with HAE with normal
C1INH levels. (C)
Acquired C1INH Deficiency
Î Clinical characteristics of angioedema episodes in patients with acquired
C1INH deficiency are similar to those for HAE attacks. (C)
Î Diagnosis of acquired C1INH deficiency involves demonstration of reduced
C1INH function, activation of complement, and reduced antigenic levels of
the first component of complement (C1). (C)
Î Acquired C1INH deficiency results from enhanced catabolism of C1INH. (LB)
Î Acquired C1INH deficiency might be associated with C1INH autoantibodies,
with or without an underlying condition (eg, lymphoma). (C)
Î The treatment of acquired C1INH deficiency is similar to that for HAE,
although with some significant differences, such as increased efficacy
of antifibrinolytic agents, decreased efficacy of C1INH replacement, and
the need to treat an underlying condition associated with acquired C1INH
deficiency. (C)
ACE-I–Associated Angioedema
Î ACE-Is are associated with angioedema in approximately 0.1% to 0.7% of
patients. (A) ARBs have been associated with angioedema less commonly. (A)
Î The management of ACE-I (or ARB)–associated angioedema is
discontinuation of the ACEI (or ARB). (A)
Î The angioedema associated with ACE-Is is likely due to impaired
degradation of bioactive peptides, such as bradykinin. (C)
Î A modest risk of recurrent angioedema exists in patients who experienced
angioedema in response to ACE-I therapy and then are switched to ARB
therapy; however, most patients who have experienced ACE-I–induced
angioedema can safely use ARBs without recurrence of angioedema. (C)
Special Cases
