The NICE Anaphylaxis guideline124 recommends that the test should be carried out preferably within 2 hours and not beyond 4 hours in order to encourage people to carry out the test early. Although a raised tryptase may occur beyond the 4-hour period, this would usually only be in a small percentage of people.
When do you draw the tryptase level?
With anaphylaxis, tryptase levels typically peak about 1 to 2 hours after symptoms begin. If a sample is drawn too early or late, results may be normal. If a histamine test is also performed, it can be compared to the tryptase levels.
When do you use a tryptase?
A tryptase test may be requested after a person's death to help determine if anaphylaxis was the cause of death. Normal tryptase results may indicate that a person's symptoms are not due to mast cell activation, or there could be a problem with sample timing.
