Angioedema is a clinical diagnosis, with no required testing in the ED.1,2,4 Leukocyte counts cannot reliably differentiate if an infection is present, as leukocytosis over 30,000 per cubic millimeter has been observed.98 C-reactive protein may be elevated in ACEi-mediated angioedema.1,4 Determining the specific type of angioedema involves specialized laboratory testing not available in the ED, including tryptase, C4, and C1-INH.1–4 These tests can be obtained in the outpatient setting and should not be routinely obtained in the ED, as they do not guide management. This evidence concerns the gene C4A and infection.