Abstract
Answer E. Tryptase
Tryptase levels should be taken at the time of anaphylaxis, up to 4 hours after and then 24 hours post onset. It is also worth noting that IgE testing for allergies after the event can help to identify anaphylaxis-triggering allergens, however false negative results can occur if the testing is done too soon after anaphylaxis because of depletion of specific IgE during anaphylaxis. IgE is unlikely to be the blood test referred to by the patient.
InnovAiT article: Anaphylaxis in general practice. DOI: 10.1177/17557380261419014.