Which is the best investigation best to confirm diagnosis of anaphylaxis?

Ans. (c) Serum TryptaseRef: Harrison 19th ed. / 2116* Elevations of tryptase levels in serum implicate mast cell activation in a systemic reaction and are particularly informative for anaphylaxis with episodes of hypotension during general anesthesia or when there has been a fatal outcome.* However, because of the short half-life of tryptase, elevated levels are best detected within 4 hours of a systemic reaction* Immunoassays using purified antigens can demonstrate the presence of specific IgE in the serum of patients with anaphylactic reactions, and intracutaneous skin testing may be performed after the patient has recovered to elicit a local wheal and flare in response to the putative antigen.