Three cases of suspected hyperthermia with remarkable elevation of serum mast cell tryptase

Tryptase is a neutral protease of human mast cells, and an important indicator of mast cell activation and degranulation in anaphylactic events. The elevation of serum mast cell tryptase (SMCT) is used for postmortem diagnosis of anaphylaxis. We have quantified the SMCT levels of 122 forensic autopsy cases with various causes of death and found only three where the SMCT levels were remarkably elevated, with values of 179, 68.9 and 69.4 ng/ml (normal level <13.5 ng/ml). The three cases were suspected to have suffered from hyperthermia, and the deaths did not seem to be related to causes of death where SMCT levels have been reported to be elevated in some cases. Two cases were patients who had been prescribed long-term neuroleptics or antidepressants, and myoglobin was detected immunohistochemically in the renal tubules of both cases. The other case died of heatstroke. A possible mechanism of hyperthermia in SMCT elevation is discussed.