Resuscitation Council UK (RCUK) Advanced Life Support (ALS) Practice Exam

In the context of diagnosing anaphylaxis, it is recommended to collect three mast cell tryptase samples. This approach is crucial for accurately assessing the level of tryptase, which can help confirm whether an anaphylactic reaction occurred.

The first sample should be taken as soon as possible after the anaphylactic event, ideally within the first hour. This timing is critical because tryptase levels peak around 1 to 2 hours post-reaction. The second sample is typically collected 24 hours later, to evaluate whether tryptase levels return to baseline, indicating resolution of the reaction. The third sample is often taken a few days later (usually around 48 hours post-event) to monitor any further changes in tryptase levels.

This three-sample strategy maximizes the likelihood of detecting an increase in tryptase levels within that critical post-reaction timeframe, ensuring a thorough evaluation of the anaphylactic episode and aiding in the diagnosis and potential management of future occurrences.