A 41 -year-old nurse is admitted to the Emergency Depanment followong an anaphylactoid reaction on the thord occasion over the last 6 months. She has acute onset stridor, facial flushing, hypoxia and hypotension. On examination hecr BP is 95/60 mmHg, pulse is 95/min and regular. 02 saturation is reduced at 91% on air.
Which of the following blood tests is most useful on biochemical confirmation of anaphylaxis?
A Serial C3 measures
B Serial CRP measures
c Serial eosinophils
Serial mast cell tryptase measures
E Serial totallgE measures
Anaphylaxis is characterised by systemic mast cell degranulation, which is associated with elevated mast cell tryptase Single measurements may however be doffocuh to interpret, at least one sample at peak symptoms, followed by onec or two in the recovery pesiod are therefore recommended.
Serial C3 measures, (Option A), is incorrect. Complement levels are more variable and therefore less useful in conforming an episode of anaphylaxis versus mast celltryptase. They may also be reduced as a result of other causes of immune activation.
Serial CRP measures, (Option B). is incorrect CRP is an acute phase protem is likely to rise more slowly versus mast cell tryptase, and is non-specific.
Serial eosinophils, (Option C), is incorrect. Eosonophils are more likely to be elevated in chronic asthma or atopic dermautis, and are less useful in evaluation of acute anaphylaxis.
Serial total lgE measures, (Option E), is incorrect. TotallgE is not useful in evaluation of allergic reactions, although antigen specifoc lgE testing may be useful in identifying a potential allergen.