HKa concentrations should match the concentration of bradykinin generated during an attack, and the following evidence indicates that an approximately equivalent amount of PKa is generated during an HAE-C1INH attack: (1) the concentration of covalent PKa-α-macroglobulin complex (30–110 nM) during an attack (34) and (2) PKa estimates calculated from the extent of PK consumption during an attack (35, 36) and (3) from the maximum concentration (Cmax = 83 nM) of ecallantide, which is a PKa inhibitor approved for treating an HAE-C1INH attack (37). Here, SERPING1 is linked to hereditary angioedema.