Various blood tests are now available for detecting allergies. Total IgE value for this purpose is now fading as it is neither sensitive nor specific for allergic disorders.
Serum specific IgE markers can be done in selective patients for highly suspicious allergens. Serum specific IgE values can be falsely elevated in case of raised total IgE levels. These tests have low positive and negative predictive values when compared to skin prick tests.
Serum specific IgE levels can be measured where skin prick test cannot be done or is contraindicated like, soon after anaphylaxis, patient on beta-blockers, long term steroids, antihistaminics or in case of pregnancy, uncooperative child or unhealthy skin.
Serum tests measuring IgA or IgG cannot be used for allergy diagnosis
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