Allergy - Food (Vegetarian), EIA

Allergy - Food (Vegetarian), EIA test measures Total IgE and specific IgE antibodies against certain vegetarian food allergens like vegetables, nuts, cereals, pulses, spices, etc. When you come in close contact with allergy-causing substances called allergens, your immune system releases immunoglobulin-E (IgE) antibodies to protect the body against specific allergens and cause allergy symptoms. Allergy symptoms include abdominal pain, cough, diarrhea, dry skin, eczema, headache, hives (urticaria) and swelling (angioedema), itchy, red or watery eyes, nausea and vomiting, shortness of breath (dyspnea), skin rash, sneezing, sore throat (pharyngitis), stuffy, itchy or runny nose, swollen lips, tongue, eyes or face, wheezing, tightness in your chest or allergic asthma. Your doctor may order this test if you have symptoms of allergy and detecting specific IgE may help manage your symptoms. Medicines may be needed to manage the symptoms. However, the best treatment for an allergy is to avoid contact with or exposure to the allergen(s).

Note:

1. The presence of allergen-specific IgE indicates sensitization to that allergen. It does not necessarily imply allergic disease. Allergy blood tests may often deliver false-positive results (around 50-60%) and they also cannot determine the severity of an allergy.
2. In patients with clinical signs and symptoms of allergy, a positive specific IgE test may either reveal sensitization induced by the allergen or sensitivity caused due to cross-reactivity (which may or may not be clinically relevant).
3. False positives can occur as a result of cross-reactivity between allergens - this can happen due to common antigenic determinants in allergens of different species. Some proteins in foods are cross-reactive with similar proteins in other foods or even environmental allergens like pollens. (e.g. false positive test for soy in a person with a peanut allergy, or a false positive test for wheat in a person with a grass pollen allergy). 
4. False negatives can occur- a negative IgE test result does not completely rule out allergic disease.
   1. Specific IgE assay against food allergens and bites of venomous insects can be false negative. In patients with clinically proven food allergies, specific IgE antibodies may remain undetected because these antibodies may be directed towards allergens that are revealed or altered during cooking, industrial processing, or digestion and therefore do not exist in the original food (allergen) for which the patient is tested.
   2. Drug allergy tests- A negative result against antibiotics (penicillin G, penicillin V, cephalosporin, ampicillin, and amoxicillin) or other drugs does not exclude the presence of a clinical hypersensitivity to these allergens. This can occur either due to non-IgE mediated hypersensitivity or timing of the blood sample (if the patient has not been exposed to the drug for a long time, the specific IgE may not be detectable) as the half-life of IgE is 2-3 days.
5. Different kits differ in the quantification of specific IgE, which varies depending on the allergen studied. Thus, specific IgE results obtained with different techniques (e.g. FEIA/ CLIA/ ELISA) are not interchangeable. The principal differences between IgE detection methods are due to the technology used, source, and quality of the allergen used in different kits.