Food Allergy Testing

Food Allergy Testing:

Food allergy testing is a process used to determine if a person has an allergic reaction to a certain type of food. It involves a combination of physical and laboratory tests to diagnose an allergy. A food allergy can produce a wide range of symptoms, including hives, abdominal pain, and difficulty breathing, that can become very serious. Food allergy testing can help identify the allergen and enable sufferers to manage their condition and avoid serious reactions.

Preparation:

Before any food allergy testing is conducted, it is important to understand the types of tests that are available, and to ensure both the patient and the doctor have a good understanding of the patient's medical history and allergies.

The patient should discuss the following with the doctor or food allergy specialist:

Any prior reactions to food
Any family history of allergies
A list of medications
Types of food the patient eats regularly

Procedure:

A skin prick test is conducted first to determine the presence of an IgE-mediated reaction. This is a simple test to see if foods have caused skin reactions through scratching, irritation and swelling.
A blood test may also be conducted to measure IgE antibodies specifically to the suspected food. This is a more accurate test for certain foods such as nuts, shellfish and eggs.
In some cases, an elimination diet may be used to determine if a certain food is causing a reaction. This involves eliminating the suspected food from the patient's diet and monitoring for any symptoms over time.

Types of Food Allergy Tests:

Skin Prick Test (SPT) - This type of test is used to determine the presence of an IgE-mediated reaction. This involves the application of a very small amount of a suspected food to the skin. If a raised, reddened area appears, it is a positive reaction.
Blood Test - This type of test measures the levels of IgE antibodies specific to a certain food. This test is more reliable than SPT as it does not give false positives, but it can take longer to get the results.
Oral Food Challenge (OFC) - This type of test is used to confirm a food allergy. The suspected food is gradually introduced in increasing amounts over a series of days to determine if there is an allergic reaction. This type of test is used to diagnose a food allergy in children.
Elimination Diet - This type of test involves eliminating the suspected food from the diet and then reintroducing it at a later date to monitor for any reactions.

Risks:

Food allergy testing can be a very accurate way to diagnose a food allergy, however there are some risks associated with the tests. For example, with the skin prick test, there is a risk of developing an anaphylactic reaction if a large enough dose of allergen is used. Blood tests can be painful and there is a risk of infection from having blood drawn.

Why:

Food allergy testing is an important part of managing a food allergy. It can identify which foods a person is allergic to, and enable the person to avoid those foods in order to prevent serious reactions. Allergy testing can also help to accurately diagnose an allergy, as opposed to relying on patient’s symptoms alone.

When:

It is recommended that food allergy testing is conducted when a person is experiencing the following symptoms:

Hives or eczema
Gastrointestinal symptoms such as nausea, vomiting or diarrhea
Respiratory symptoms such as sneezing, wheezing, or difficulty breathing
Anaphylaxis, which is a serious and life-threatening reaction

In addition to the above symptoms, food allergy testing may be recommended for a person with a family history of food allergies, or who is at risk of developing a food allergy.