Mast Cell Tryptase
Mast cell tryptase is released during the anaphylactic reaction and may be measured in the blood.
It reaches its peak blood concentration approximately 1-2 hours after the reaction. This is useful to aid later diagnosis and treatment and can help in the diagnosis in uncertain cases.
The half-life of tryptase is short (approximately 2 hours) and concentrations may be back to normal within 6-8 hours, so timing of any blood samples is very important.
Measurement of mast cell tryptase is recommended in all patients with suspected anaphylaxis when the diagnosis remains uncertain.1
The Resuscitation Council recommend that three tryptase levels are taken:
- As soon as resuscitation has started
- 1-2 hours after symptoms have started
- 24 hours later or in convalescence (some people have raised baseline tryptase levels)
Current NICE guidelines recommend all adults and young people over 16yrs who present with a suspected anaphylactic reaction should have a sample taken as soon as possible after emergency treatment has started, and a second sample ideally within 1-2 hours (but no later than 4 hours) from the onset of symptoms.
Testing should be considered in all children under 16yrs who present with suspected venom-related, drug-related or idiopathic anaphylaxis only.