A Forgotten Cause of Allergy at ER That Is Still Difficult to Diagnose and Treat at Poor Resource Setting: Angioedema after Using Angiotensin Converting Enzyme Inhibitors for 4 Years

Table 1

Diagnostic tests to help distinguish among angioedema types (table reproduced from Bernstein JA et al. (2017), [under the Creative Commons Attribution License/public domain]).

Type of angioedema	C1-INH concentration	C1-INH function	C4 concentration	Tryptase concentration
HAE type I	Low	Low	Low	Normal
HAE type II	Normal or High	Low	Low	Normal
HAE with normal C1-INH	Normal	Normal	Normal	Normal
Acquired AE	Low	Low	Low	Normal
ACEi-induced AE	Normal	Normal	Normal	Normal
Histamine-mediated anaphylaxis	Normal	Normal	Normal	Normal or Elevated

In blood drawn within 4–6 h of onset of attack.
ACEi: angiotensin-converting enzyme inhibitor; AE: angioedema; C1-INH: C1 inhibitor; HAE: hereditary angioedema.