Fast Five Quiz: Allergy Triggers

Praveen Buddiga, MD


August 23, 2019

Immediate hypersensitivity skin testing is the most useful method to detect immunoglobulin E antibody against mold allergens. Testing can be performed by using the prick or intradermal method. The preferred sites are the upper part of the back for the prick method and the arms for the intradermal method. Histamine and normal sodium chloride solution are most commonly used as positive and negative control solutions, respectively. Results are recorded 15 minutes after the test is performed. A wheal diameter > 3 mm above the reaction of the negative control solution is considered a positive result. Mold allergen extracts used for the skin test depend on the prevalence of various molds in the region as identified with annual atmospheric sampling. The most common molds include Alternaria, Aspergillus, Curvularia, Epicoccum, Fusarium, Helminthosporium, Hormodendrum, Mucor, Penicillium, Phoma, Rhizopus, and Stemphylium species.

A positive RAST result confirms allergen-specific immunoglobulin E in the peripheral blood. The test is indicated in individuals who have clinically significant dermatographism or extensive skin disease, those who cannot discontinue antihistamines or other medications with antihistamine actions (eg, tricyclic antidepressants), or those who have a history of anaphylactic reaction (direct application of the suspected allergen may precipitate recurrent anaphylaxis). A RAST is not generally considered as sensitive as skin testing.

In patients with allergic rhinitis, sinus radiography is not usually necessary unless it is used to look for superimposed sinusitis.

The presence of > 10% eosinophils in the nasal secretion supports the diagnosis. Hansel staining is used to identify eosinophils. Eye swab results can be used to diagnose allergic conjunctivitis. If neutrophils are present in > 90% of the cell population, bacterial infection should be considered.

Read more about the diagnosis of allergic rhinitis related to mold.


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