Mast cell tryptase testing after suspected anaphylaxis

Mast cells can release tryptase during a severe allergic reaction. Clinicians interpret the result alongside the symptoms, examination, exposure history and response to treatment; the blood test does not replace clinical assessment or delay adrenaline.

A rise above the person's usual baseline can support mast-cell activation. The value may be less informative if blood is collected too early or too late, and some forms of anaphylaxis cause little or no measurable rise.

Doctors may compare an acute sample with a later baseline sample taken after recovery. A persistently raised baseline can have causes other than the recent reaction and may lead to specialist assessment rather than an automatic diagnosis.

Keep the discharge record and record the suspected trigger, timing, symptoms and treatments received. Attend follow-up even if the tryptase result was normal. An allergy specialist can decide whether a baseline sample, targeted allergy testing, an adrenaline auto-injector or a written emergency plan is appropriate.

Do not deliberately re-expose yourself to a suspected food, medicine or sting to test the diagnosis. Follow the avoidance advice given at discharge until the clinical history has been reviewed.

Call emergency services immediately for trouble breathing, throat or tongue swelling, wheezing, collapse, faintness, confusion, or rapidly developing symptoms affecting more than one body system after a possible allergen exposure. Use prescribed adrenaline promptly according to the personal action plan, then obtain emergency assessment even if symptoms improve.

Blood sampling is secondary to treatment. Never wait for a tryptase test or its result before using prescribed emergency medication or calling for help.

Ask when each sample was taken, whether an acute result will be compared with a baseline, what trigger is suspected, and which exposures to avoid meanwhile. Confirm how to recognise recurrence, how to use prescribed adrenaline, and where the emergency plan should be kept.