Hi everyone,
Today, we had noon rounds on the topic of drug reactions, allergies and anaphylaxis.
We recently chatted about Anaphylaxis at Morning Report last week, but I wanted to include an interesting diagnostic pearl. The following test is actually available at LHSC and is recommended by the allergists when you see a patient whom you are treating as anaphylaxis, but perhaps are not sure that this is the definitive diagnosis.
Confirming the Diagnosis: The Role
of Tryptase measurement?
Elevated levels of total
tryptase in the serum can be useful to help distinguish anaphylaxis from other
conditions on the DDx (i.e. vasovagal episode, MI, benign flushing, carcinoid
syndrome, etc—as these other disorders are normally not associated with an
elevation of total tryptase).
An increase in tryptase
indicates that mast cell activation has occurred.
Bottom Line: some hospitals allow you to order tryptase levels;
collection of tryptase measurements should be done if the diagnosis of
anaphylaxis is being considered. Elevations in tryptase correlate with
hypotension and support the diagnosis of anaphylaxis, however; normal levels do
not exclude anaphylaxis (especially in food-induced reactions). The specificity
and sensitivity of tryptase elevations have not been elucidated. Try to collect
the sample within 1-3 hours of the event. Generally, large elevations of the
tryptase level persist for several hours after the onset of the query anaphylaxis.
Thank you all for a great first block!
-Jade
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