TRYPTASE - serum

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Specimen: 5 mL blood in plain tube. The samples should be obtained within 6 hours of the event under investigation, with 1-2 hours being optimal. Post-mortem blood is also suitable, if collected within 4 days of death, provided that death did not follow the event by less than 30 minutes.

Method: Immunoassay.

Reference Interval: <2 U/L.

Application: To identify anaphylaxis as a cause of collapse or death, eg during anaesthesia, after insect sting, administration of drugs or biological agents (eg desensitisation vaccines).

Interpretation: Increased tryptase levels indicate mast cell degranulation with mediator release, thereby demonstrating an allergic basis for the reaction. A negative result does not exclude an allergic basis.

Reference: Schwartz LB. In: Huston DP ed. Diagnostic Laboratory Immunology, WB Saunders 1994.

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