Choosing Wisely®: Allergy Testing
50 million Americans are affected each year by allergy symptoms and environmental allergies may be on the rise, with prevalence of food allergies among U.S. children increasing by 18% between 1997 and 2007. As public awareness increases, physicians may receive more requests for allergen testing.
With over 150 specific food and environmental IgE assays available on the Cleveland Clinic test menu embedded within multiple large panels of allergens, the importance of “choosing wisely” is clear. According to Dr. Ansari, medical director of the immunopathology lab, ‘ Remember that laboratory testing for specific IgE levels to allergens only indicates sensitization, not disease. The patient’s history is still the most important tool in evaluating allergies; tests can confirm an impression and should always be used in conjunction with a positive history for proper diagnosis. Ordering a number of panels of allergy testing as a method of screening leads to over-utilization of lab facilities and facilitates sub-optimum patient care’.
- Do not perform an “indiscriminant” (i.e. without history) battery of IgE testing in evaluation of allergy1
- Don’t perform food IgE testing without a history consistent with food allergy1,2
- Do not perform IgG testing in evaluation of allergy1
1American Academy of Allergy, Asthma & Immunology | 2American Academy of Pediatrics
A clinical history should always be obtained prior to considering laboratory testing for allergies. Laboratory tests are best used for confirmation in patients in which the pre-test clinical probability of allergic disease is high; these tests are not very useful as screening for patients with low probability of disease. Diagnosis of allergic disease cannot be solely based on laboratory results. Laboratory evidence of IgE sensitization does not always correlate with clinically significant allergy so broad testing may not be useful and may lead to unnecessary exclusion of foods. Immunoglobulin G (IgG) molecules signify exposure but their correlation to intolerance or allergy is not well understood. Therefore, IgG levels are unreliable as a diagnostic tool for determining food allergies.
Branum AM, Lukacs SL. Food allergy among U.S. children: trends in prevalence and hospitalizations. NCHS Data Brief. 2008;10:1-8.
Hamilton RG. To the Editor: Allergen-specific IgE serologic assays define sensitization, not disease. Cleve Clin J Med. 2016;83: 326-327.
Muraro A, Werfel T, Hoffmann-Sommergruber K, Roberts G, Beyer K et al. EAACI food allergy and anaphylaxis guidelines: diagnosis and management of food allergy. Allergy. 2014 Aug;69(8):1008-25.
Siles RI, Hsieh FH. Allergy blood testing: A practical guide for clinicians. Cleve Clin J Med. 2011;78:585-592.
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