Hereditary Angioedema (HAE)
C1 Esterase Inhibitor Deficiency Profile
Aid clinicians in obtaining an appropriate diagnosis of hereditary angioedema (HAE). The profile begins with complement C4 and complement C1 esterase inhibitor with reflexing, if required, to complement C1 esterase inhibitor, functional to distinguish HAE type I from type II. If the results are not consistent with HAE consider other types of angioedema and/or retesting during an acute attack.
Rheumatoid factors (>200 IU/mL) significantly increase the apparent C4 concentration. This profile is not intended for the diagnoses of estrogen-dependent, estrogen-associated, drug-induced, or idiopathic angioedema. Also note that patients taking anabolic steroids may have falsely elevated C4 values thus limiting the effectiveness of the profile’s logic. Consider retesting the patient after discontinuation of anabolic steroids.
Serum, frozen and room temperature
Three aliquots: one tube 0.5 mL frozen, two tubes 1 mL each at room temperature
Three aliquots: one tube 0.1 mL frozen, two tubes 0.5 mL each at room temperature
Gel-barrier tube (preferred) or red-top tube. Note: Since specimen must be drawn on ice, plain red-top tubes will not clot as well as the use of clot-activated gel tubes.
Collect sample on ice. Separate serum from cells in a refrigerated centrifuge. If a refrigerated centrifuge is not available, chill centrifuge tube carriers before centrifuging. Transfer aliquots of serum to each of three plastic transport tubes. Freeze the required 0.5 mL frozen aliquot immediately at -20°C.
Frozen sample should not be stored at room temperature (15°C to 30°C) for longer than six hours.
Required room temperature samples are stable for three days, frozen samples for 14 days.
Plasma specimen; specimen not drawn on ice; stored specimen not frozen; gross bacterial contamination; excess lipemia; hemolysis; separate specimens not received (room temperature and frozen)