SERPING1 and allergic disease: The HAE-RT tool was proposed for emergency department use and contains 4 steps: (1) assess airway stability in patients with recurrent angioedema; (2) consider HAE in patients with no response to allergy treatments and past recurrent abdominal pain or swelling; (3) prompt treatment (with plasma-derived C1INH, icatibant, or, if others are not available, fresh frozen plasma); and (4) follow-up (referral to allergist to confirm diagnosis).75