After suspected anaphylaxis in an adult or young person aged 16 years or older, take timed blood samples for mast cell tryptase testing as follows:
a sample as soon as possible after emergency treatment has started
a second sample ideally within 1 to 2 hours (but no later than 4 hours) from the onset of symptoms. [2011]
After suspected anaphylaxis in a child younger than 16 years, consider taking blood samples for mast cell tryptase testing as follows if the cause is thought to be venom-related, drug-related or idiopathic:
a sample as soon as possible after emergency treatment has started
a second sample ideally within 1 to 2 hours (but no later than 4 hours) from the onset of symptoms. [2011]
Inform the adult, young person or child (or their parent or carer, as appropriate) that a blood sample may be required at follow-up with the specialist allergy service to measure baseline mast cell tryptase. [2011]