Test for Allergic Rhinitis
When and which tests would you recommend if you are suspecting an allergic cause of allergic rhinitis? Are there age-specific tests for food/pet allergies?
Bela Kale
Two types of tests are generally used for allergies responsible for rhinitis symptoms. Both allergy skin tests and RAST (radioallergosorbent tests) are designed to detect allergen-specific IgE. Skin tests are generally performed by certified allergists, and have the advantages of being relatively quick and inexpensive. A wide variety of allergenic extracts are available for skin testing, and this technique is quite sensitive. RAST tests are available from most reference laboratories, and with a small amount of serum, tests for many specific allergies can be performed. The RAST tests have the advantage of not depending on a skin response, and therefore RAST results are not affected by skin rashes or the use of antihistamines. Either of these factors can obscure the results of skin tests.
Age, exposure to different environments at home and at work, and local patterns of pollens and mold need to be considered when ordering tests to detect allergies. Food allergies can develop quite early, and skin tests for foods are commonly used in the first year of life if there are clinical indications of allergy. Sensitization to indoor allergens such as cat, dog, and house dust mite is unusual before the age of 1 year, but progressively becomes more common throughout early childhood. After the age of 3 years, the percentage of children sensitized to outdoor allergens increases, reaching a peak during the teen years.
An additional point to consider is that isolated respiratory symptoms, including rhinitis, are generally not caused by a food allergy. Allergic reactions to foods should generally be considered when (1) there is a temporal association between ingestion of the food and the adverse reaction, (2) the adverse reaction is reproducible each time a sufficient quantity of the food is eaten, and (3) typical organ systems are involved. The most common clinical manifestations of food allergy include gastrointestinal complaints such as abdominal pan, vomiting, and tingling or itching in the mouth; skin symptoms such as flushing, hives, and itching; and respiratory symptoms such as tightness in the throat or wheezing. The respiratory symptoms, when present, usually occur together with skin or gastrointestinal manifestations.
When and which tests would you recommend if you are suspecting an allergic cause of allergic rhinitis? Are there age-specific tests for food/pet allergies?
Bela Kale
Two types of tests are generally used for allergies responsible for rhinitis symptoms. Both allergy skin tests and RAST (radioallergosorbent tests) are designed to detect allergen-specific IgE. Skin tests are generally performed by certified allergists, and have the advantages of being relatively quick and inexpensive. A wide variety of allergenic extracts are available for skin testing, and this technique is quite sensitive. RAST tests are available from most reference laboratories, and with a small amount of serum, tests for many specific allergies can be performed. The RAST tests have the advantage of not depending on a skin response, and therefore RAST results are not affected by skin rashes or the use of antihistamines. Either of these factors can obscure the results of skin tests.
Age, exposure to different environments at home and at work, and local patterns of pollens and mold need to be considered when ordering tests to detect allergies. Food allergies can develop quite early, and skin tests for foods are commonly used in the first year of life if there are clinical indications of allergy. Sensitization to indoor allergens such as cat, dog, and house dust mite is unusual before the age of 1 year, but progressively becomes more common throughout early childhood. After the age of 3 years, the percentage of children sensitized to outdoor allergens increases, reaching a peak during the teen years.
An additional point to consider is that isolated respiratory symptoms, including rhinitis, are generally not caused by a food allergy. Allergic reactions to foods should generally be considered when (1) there is a temporal association between ingestion of the food and the adverse reaction, (2) the adverse reaction is reproducible each time a sufficient quantity of the food is eaten, and (3) typical organ systems are involved. The most common clinical manifestations of food allergy include gastrointestinal complaints such as abdominal pan, vomiting, and tingling or itching in the mouth; skin symptoms such as flushing, hives, and itching; and respiratory symptoms such as tightness in the throat or wheezing. The respiratory symptoms, when present, usually occur together with skin or gastrointestinal manifestations.
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