Elevated postmortem tryptase in the absence of anaphylaxis.

Elevations in tryptase, a recently discovered mast cell enzyme, have been proposed as a postmortem indicator of fatal anaphylaxis. The previous studies had limited numbers of controls and thus the specificity of the test with postmortem samples was not known. Therefore, tryptase was evaluated in postmortem blood samples from 49 autopsy cases where there was no evidence of fatal anaphylaxis. The tryptase was above the normal serum threshold of 1 nanogram/mL (ng/mL) in 31 of these cases. Twenty-four cases had values in the 1 to 5 ng/mL range, two cases were between 5 and 10 ng/mL, and five were greater than 10 ng/mL. One autopsy specimen had a tryptase value of 106 ng/mL. The postmortem interval and the specimen storage condition did not appear to correlate with these elevations in tryptase. Although elevations in the postmortem tryptase remain an important supporting finding in the diagnosis of fatal anaphylaxis, it should not be used alone as the sole criterion for the postmortem diagnosis of anaphylaxis.