From the Guidelines
Elevated tryptase levels in anaphylaxis typically last for 6 hours, with peak levels reached 1-2 hours after the onset of symptoms 1.
Key Points
- The duration of elevated tryptase levels can vary, but serum tryptase levels usually peak 60-90 minutes after the onset of anaphylaxis and persist for up to 6 hours 1.
- The best time to measure serum tryptase levels is between 1-2 hours after the onset of symptoms, but no longer than 6 hours 1.
- Tryptase has a half-life of about 2 hours in the circulation, which means its concentration falls rapidly following an anaphylactic reaction 1.
- It's essential to consider the timing of sample collection when interpreting tryptase levels, as intravenous fluid replacement can dilute the blood and cause a fall in tryptase concentration 1.
- While tryptase levels can be helpful in diagnosing anaphylaxis, they are not always elevated in anaphylactic reactions, and a normal concentration does not rule out anaphylaxis 1.
From the Research
Duration of Elevated Tryptase Levels in Anaphylaxis
- The duration of elevated tryptase levels in anaphylaxis can vary, with peak levels occurring at different times after the onset of symptoms 2, 3, 4.
- One study found that tryptase levels peaked between 30 minutes to 6 hours after anaphylactic shock or anaphylaxis 2.
- Another study measured tryptase levels at 1-2 hours, 4-6 hours, and 12-24 hours after the onset of anaphylaxis and found that tryptase concentrations were significantly higher at 1-2 hours than at later time points 3.
- A study on food allergic reactions found that peak tryptase levels occurred at 2 hours after the onset of symptoms and correlated with symptom severity 4.
Factors Affecting Tryptase Levels
- The severity of anaphylaxis can affect tryptase levels, with more severe reactions associated with higher tryptase levels 3, 4, 5.
- The type of allergen triggering the anaphylaxis can also impact tryptase levels, with drug-induced anaphylaxis associated with higher tryptase levels than food-induced anaphylaxis 3.
- Baseline tryptase levels can be a marker for the severity of anaphylaxis, with higher levels associated with more severe reactions 5.
Clinical Utility of Tryptase Measurements
- Tryptase measurements can be useful in diagnosing anaphylaxis, particularly in cases where the diagnosis is uncertain 2, 3, 4.
- However, tryptase levels may not be elevated in all cases of anaphylaxis, and serial measurements may be needed to confirm mast-cell participation in milder reactions 2, 3.
- The clinical utility of tryptase measurements in acute allergic reactions needs further study, particularly in relation to other markers such as histamine levels 6.