Q: What is the advantage of measuring tryptase in anaphylaxis over histamine?



Answer; 

Plasma histamine levels need to be measured in less than 30 minutes after anaphylaxis event, though metabolites of histamine accumulated in urine stay elevated for few hours and can be measured. Tryptase has advantage of longer time window, and can be measured from 15 minutes to 3 hours after onset of symptoms. There are two tests for tryptase

1) Total tryptase and 
2) Mature tryptase

Mature tryptase correlates more with the anaphylaxis but is not widely available. Total tryptase can be measured and followed serially.

Diagnosis of anaphylaxis is usually made on clinical grounds and above tests are more of academic interests, or if diagnosis is in question.



Reference
Schwartz LB. Diagnostic value of tryptase in anaphylaxis and mastocytosis. Immunol Allergy Clin North Am 2006; 26:451.