Is unrecognized anaphylaxis a cause of sudden unexpected death?

BACKGROUND

Serum tryptase levels reflect mast cell activation and correlate with anaphylactic reactions. Elevated post-mortem serum tryptase levels have been found in witnessed fatal anaphylaxis.

OBJECTIVE

This study was designed to examine whether or not unwitnessed anaphylaxis may be a hitherto unrecognized cause of sudden unexplained death.

METHODS

Mast cell tryptase was measured by immunoassay in 68 post-mortem sera remaining from a previous study which reported elevated venom-specific IgE antibodies in 22 (23%) of 94 victims of sudden unexpected death. Autopsies were performed in all cases. The cause of death was independently reported by pathologists unfamiliar with the nature of this study.

RESULTS

Serum tryptase levels were elevated (> 10 ng/mL) in nine of 68 cases. The levels could not be predicted from the clinical circumstances surrounding death. Sera from four individuals contained both elevated tryptase and previously reported elevated venom-specific IgE.

CONCLUSIONS

We conclude that mast cell activation may accompany up to 13% of sudden unexpected deaths in adults. Measurement of both tryptase and specific IgE antibody levels in post-mortem sera from persons experiencing sudden, unexpected death may identify a small subset of cases due to clinically unrecognized fatal anaphylaxis, including those due to insect stings.