Allergies (IgE) – Blood Test
Allergy Conditions
When an allergic reaction occurs, the immune system reacts by releasing cells called antibodies. The foods and inhaled particles that provoke the release of antibodies are called allergens. Two commonly produced antibodies are IgG (immunoglobulin G) and IgE (immunoglobulin E).
Conditions related to IgE allergies:IgE reactions occur within minutes or hours of exposure and release inflammation causing chemicals like histamine, which are responsible for most of the symptoms associated with IgE allergic reactions. These symptoms may include:
Redness and swelling: are due to the release of inflammation-causing chemicals like histamine which cause the blood vessels to dilate, producing redness and swelling.
Tightening of airways: The release of inflammation-causing chemicals like histamine can cause airway congestion and constriction.
Itching: The release of inflammation-causing chemicals can cause stimulation of nerve endings, which produce pain and itching on the skin surface.
Why Test For Food Allergies?
- IgE testing is useful for unexplained allergic reactions like hives, or for uncovering allergies to inhaled particles. IgE Allergy Testing requires a needle puncture to withdraw blood, and the blood is centrifuged and the red cells removed, leaving clear serum. The serum comes to the laboratory for analysis.
Talk to your health care provider about getting a food allergy test done.
What Do Allergy Test Results Mean?
IgE Immediate Hypersensitivity ReactionsIgE reactions to food occur within minutes to hours after the food is consumed, and so are usually easy to diagnose. You eat a food and you get symptoms like swelling and difficulty breathing right away - so you are motivated to avoid eating that food again! These kinds of allergic reactions usually remain for life IgE reactions primarily affect the skin, lungs and digestive tract. The allergy test report categorizes reactions as no, low, moderate or high. Unlike IgG allergies, eliminating IgE food allergens does not generally cause withdrawal symptoms or cravings.
Allergies to inhaled allergens are difficult to identify without testing. These allergens include things like pollens, animal dander, dust mites and molds. Inhalant allergies are strictly IgE reactions.
What does No Reaction really mean?Allergy tests offer a snapshot of the immune response to various foods. However, sometimes a no reaction result is recorded when an individual knows he/she is intolerant of a specific food. There are several reasons why this can occur. Foods that have not been consumed for two or three weeks prior to the test may not provoke an allergic response because there are no allergens to react to. In other words, if you don't eat it, you won't produce antibodies to it, so no reaction occurs. (The exception to this is if there is cross-reactivity with another food group).
Another possibility is that the reaction you experience is actually an intolerance, not an allergy. Food intolerances may mimic the symptoms of a food allergy but are not the direct result of an antibody-antigen reaction. For example, lactose intolerance is due to a deficiency in the enzyme lactase, the enzyme responsible for the digestion of the milk sugar lactose. Adverse reactions to food additives may also be defined as food intolerance. Sometimes a lack of digestive enzymes or stomach acid can result in a food intolerance. It is also possible, based on a previous negative episode with a specific food (e.g. food poisoning) to have a physical reaction to that food, because of the negative experience associated with it.
**Description courtesy of Rocky Mountain Analytical