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Article by Ron Fisher, ND

When Should I have an Allergy Test?

Many common symptoms can relate to ingestion of foods, beverages and preservatives.  These symptoms include fatigue, headache, anxiety, itchy runny nose, puffy eyelids, skin conditions, gastrointestinal disorders, and may lead to more serious conditions including arthritis, autoimmune disease, migraines, and other chronic diseases.

If you can’t connect the symptom to a specific food then a blood test may be useful to help with unexplained symptoms.

Airborne substances can also cause allergy symptoms.  Skin Prick Tests can be a reliable way of determining respiratory allergies to airborne substances, allergies to insect bites and allergies to penicillin. 

In Australia you need a referral from your GP and then usually have to join the waiting list at a local hospital so that potential anaphylactic reactions during the test can be managed. 

There are blood tests called “Inhalant Allergy Panel IgE and Inhalant Allergy Panel IgG tests” that provided a reliable alternative to a skin prick test

Based on the knowledge that adverse reactions to foods can be caused by a wide range of factors and involve many parts of the body, it is understandable that diagnostic tests for food reactions may not test all possible causes.

IgE food allergy testing should be used for the assessment of immediate food allergies (generally associated with anaphylactic reactions), whilst IgG food allergy tests analyse delayed food allergies, and ALCAT panels can analyse delayed food allergies as well as reactions to foods that involve histamine release, cytokine release and/or degranulation of leucocytes.

The IgE mediated food allergy is well known, easily diagnosed and usually results in physical symptoms within minutes. The existence and classification of IgG food allergies have been more controversial. The IgG food reactions are difficult to diagnose (without a test) because the time between consumption of the offending food and the physical response may be delayed; even up to 3 days later. The symptoms are also often subtle. In many cases ingestion of the offending food paradoxically masks the symptoms temporarily.
An anaphylactic food reaction is an immediate, severe and often life-threatening reaction to a food. This is mediated by an IgE immune response as set out above.

For the Food IgG Allergy Panels, you must include as many of the foods that are being tested in the two weeks prior to specimen collection. If foods are not included in the diet during this time false negative results may be obtained, as recent exposure to these foods may be required for antibodies to be present in the blood. Foods, however, that have caused an anaphylaxis reaction in the past should never be reintroduced into the diet without the specific guidance of an allergy specialist. For the ALCAT test you do not have to eat any specific foods prior to testing

The testing lab should advise you about medications that can interfere with the tests.  For example for the IgG and IgE allergy tests you usually avoid using anti-histamines, anti-inflammatories and any other immunosuppressive medications for two weeks prior to testing. 

However, never discontinue prescription medications without first consulting your doctor.

For more Allergy related information view the >> Allergy Research and Discussion Articles or see the >> Allergy Article  Menu

For Allergy Test related question please contact us.

12 Oct 2010

Article/Information supplied by Ron Fisher, ND

Disclaimer - Any general advice given in any article should not be relied upon and should not be taken as a substitute for visiting a qualified medical Doctor.