Background Sheffield National Adverse Reactions Consultancy Service (NARCOS) investigates and triages suspected perioperative anaesthetic reactions to allergy clinics, using serial tryptase samples, urinary methylhistamine and clinical information on a pro forma request.

Objective To determine if current UK guidelines on serial tryptase samples are achieved and describe the patterns of tryptase release.

Method A retrospective review of 3455 NARCOS cases. Tryptase and clinical details were analysed. 1746 had sufficient clinical information to grade the reactions according to the Ring and Messmer scale.

Results 98% provided two or more acute samples, but only 60% supplied clinical information. 308 patients never dropped within the reference range over three samples.

Conclusions Good compliance with UK guidelines for tryptase measurements is achievable in this long-term cohort, but obtaining clinical details at referral remains a challenge. Sample sequence labelling and apparent timing may be misleading. Baseline tryptase may frequently need to be rechecked in allergy clinics to estimate true peak-to-trough changes.