Tryptase
An enzyme stored inside mast cells — immune cells central to allergic reactions. A sharp rise during and shortly after a severe reaction helps confirm anaphylaxis, while a persistently high baseline level points toward mastocytosis, a condition of too many mast cells.
What it measures
Tryptase is an enzyme packaged inside mast cells, the immune cells that drive allergic and anaphylactic reactions by releasing histamine and other mediators. When mast cells are activated in a severe allergic reaction, they release tryptase into the blood, where it can be measured. This gives the test two distinct uses. The first is confirming anaphylaxis: a blood sample taken during or within a few hours of a suspected severe reaction can show a transient spike in tryptase, which then returns to normal — comparing this peak with a later baseline sample helps confirm that mast cells were massively activated, supporting the diagnosis after the event. The second use is quite different: a tryptase level that is persistently raised at baseline, when the person is well, suggests an increased overall mast-cell burden. This is the key screening clue for mastocytosis and related mast-cell disorders. A very high or rising baseline may prompt further testing, including for a genetic mast-cell trait. So tryptase is read in two ways — a transient rise around a reaction (anaphylaxis) versus a persistently elevated baseline (mast-cell disorder).
What a high value can mean
- A transient rise during/after a reaction — supports anaphylaxis; the sample must be timed correctly and compared with a baseline.
- A persistently high baseline — suggests an increased mast-cell burden, the key clue for mastocytosis.
- Systemic mastocytosis or a mast-cell activation disorder.
- Hereditary alpha-tryptasemia — a common genetic cause of a modestly raised baseline.
- Sometimes raised in some blood disorders or advanced kidney disease.
What a low value can mean
- A normal baseline — the expected result; makes an underlying mast-cell disorder less likely.
- A normal level after a suspected reaction — does not fully exclude anaphylaxis, as timing matters and not every reaction raises tryptase.
When to discuss with a doctor
Tryptase is a specialist test used in two situations. Around a severe allergic reaction, a correctly timed sample helps confirm anaphylaxis after the event and is interpreted with a later baseline — but it never guides emergency treatment, which is given immediately on clinical grounds. Away from a reaction, a persistently raised baseline tryptase is the main screening clue for mastocytosis and related mast-cell disorders, and prompts referral to an allergy or haematology specialist for further assessment. A normal result after a reaction does not rule anaphylaxis out. Mediora.AI shows a tryptase result in context — flagging a raised baseline that may warrant specialist review and noting the timing that a post-reaction sample needs; the interpretation belongs with your doctor.