Anaphylaxis - Diagnosis

Diagnosis

Anaphylaxis is diagnosed based on clinical criteria. When any one of the following three occurs within minutes/hours of exposure to an allergen there is a high likelihood of anaphylaxis:

1. Involvement of the skin or mucosal tissue plus either respiratory difficulty or a low blood pressure
2. Two or more of the following symptoms:-

   a. Involvement of the skin or mucosa

   b. Respiratory difficulties

   c. Low blood pressure

   d. Gastrointestinal symptoms

3. Low blood pressure after exposure to a known allergen

During an attack, blood tests for tryptase or histamine (released from mast cells) might be useful in diagnosing anaphylaxis due to insect stings or medications. However these tests are of limited utility if the cause is food or if the person has a normal blood pressure, and they are not specific for the diagnosis.