Pathology Handbook

Adverse drug reaction


Anaphylactic drug reaction, plasma tryptase

Clinical Indications

Intravenous 'drug' administration may cause immediate hypersensitivity (anaphylactic), or histamine release (anaphylactoid) reactions. These may range from minor (flushing, urticaria) to major (bronchospasm, cardiovascular collapse). They are due to the release of histamine and other vasoactive chemicals: they can be mimicked by other conditions - underlying pathology or pharmacological effects.

Test Includes

Plasma tryptase (urine methylhistidine is no longer available)

Request Form

Request on ICE


Analysed by referral laboratory if specific criteria met.

Specific Criteria

Confirmation of anaphylactic drug reaction.

Turnaround Time

1 week


Blood series


5 ml


Vacutainer lemon top

Vacutainer purple top

Serum samples (SST or red-top) are also acceptable.


Blood taken within 60 minutes, then 3 and 24 hours after reaction; separate, purple-topped  samples should be collected for FBC and differential.

Lab Handling

Measured at Southend Pathology.  If levels are raised, sample diluted on site