Histamine is not a frequently ordered test. Anaphylaxis is usually diagnosed without testing for histamine or tryptase, and mastocytosis is rare. Histamine and tryptase tests are sometimes ordered when a person has symptoms that suggest anaphylaxis, especially when the diagnosis is not clear and/or the symptoms are recurrent. Symptoms of anaphylaxis include:
Many of these symptoms are also seen with other conditions.
- Difficulty breathing, wheezing
- Itching, often with visible hives
- Light-headedness or dizziness
- Low blood pressure
- Swelling of the throat, face, tongue, and/or eyes
Testing may also be ordered when a healthcare practitioner suspects that a person may have mastocytosis or a mast cell activation disorder. People with these disorders have many of the same symptoms and signs as persons with severe allergies, but without any specific trigger, such as exposure to certain foods (e.g., peanuts) or a bee sting. Persons with systemic mastocytosis may have signs and symptoms such as peptic ulcers, chronic diarrhea, joint pain, enlarged liver, spleen or lymph nodes, rashes or characteristic red, blistering lesions that may be present singly or by the hundreds.