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Allergen Testing



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May 2014

According to the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, asthma and allergic diseases are common for all age groups in the United States. Asthma affects more than 17 million adults and more than 7 million children. Hay fever, respiratory allergies, and other allergies affect approximately 10% of children under age 18. In addition, food allergies affect an estimated 5% of children under age 5 and 4% of older children (5-17 years) and adults.

Allergies are a form of hypersensitivity reaction, typically in response to harmless environmental allergens such as pollen or food. Clinical manifestations of immediate hypersensitivity (allergic) diseases are caused by the release of proinflammatory mediators (histamine, leukotrienes, and prostaglandins) from immunoglobulin E (IgE)-sensitized effector cells (mast cells and basophils) when cell-bound IgE antibodies interact with the allergen.

In individuals predisposed to develop allergic disease, the sequence of sensitization and clinical manifestations proceed as follows: eczema and respiratory disease (rhinitis and bronchospasm) in infants and children younger than age 5 due to food sensitivity (milk, egg, soy, and wheat proteins) followed by respiratory disease (rhinitis and asthma) in older children and adults due to sensitivity to inhalant allergens (dust mite, mold, and pollen inhalants).

In vitro serum testing for IgE antibodies provides an indication of the immune response to allergens that may  be associated with allergic disease. Testing may also be useful to identify allergens responsible for anaphylaxis, to confirm sensitization to particular allergens prior to beginning immunotherapy, and to investigate the specificity of allergic reactions to insect venom allergens, drugs, or chemical allergens.

The allergens chosen for testing depend upon the age of the patient, history of allergen exposure, season of the year, and clinical manifestations.

Mayo Medical Laboratories offers 3 types of allergen testing:

Single allergen testing

This test is useful to confirm the allergen specificity in patients with clinically documented allergic disease. Therefore, requests for these tests should be made after a careful and comprehensive medical history is taken. Utilized in this manner, a single allergen immunoglobulin E (IgE) antibody test is cost effective. A positive result may indicate that allergic signs and symptoms are caused by exposure to the specific allergen.

Panel allergen testing

The multiallergen IgE antibody panel, combined with measurement of IgE in serum, is an appropriate first-order test for allergic disease. A pooled allergen reagent is used for each panel; therefore, the panel is reported with a single qualitative result. Panel testing requires less specimen volume and less cost for ruling out allergic response; however, individual (single) allergen responses cannot be identified. Positive results indicate the possibility of allergic disease induced by 1 or more allergens present in the multiallergen panel. In cases of a positive panel test, follow-up testing must be performed to differentiate between individual allergens in the panel. Negative results may rule out allergy, except in rare cases of allergic disease induced by exposure to a single allergen.

Profile allergen testing

In a profile test, a number of related allergens are grouped together for ordering convenience. Each is tested and reported individually. Specimen volume requirements are the same as if each allergen were ordered individually.

 


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