Allergy Testing

What is Allergy Intolerance Testing?

Allergy intolerance testing or allergy testing is a range of tests which are used to determine or identify substances to which a person is allergic. Allergy is the term used to describe an adverse reaction by the body in relation to contact with a particular substance. The word ‘allergy’ was coined by Clemens Von Pirqet a Viennese paediatrician & is derived from the Greek word allos meaning ‘other’ & ergon meaning work. He noticed that some of his patient’s had sensitivity to certain foods, dust or pollen. Almost 1 in 4 people in the UK are affected by allergies. On average this figure increases year on year by 5%.

What Is An Allergic Reaction?

An allergic reaction occurs when you come into contact with an allergen. (The most common allergens are nuts, dust mites & pollen. The reason for the reaction is the protein contained within these substances causes a bad reaction. It is important to note that some drugs can also cause an allergic reaction such as penicillin. Whilst these drugs don’t contain protein they cause an adverse reaction by binding with proteins contained within the body. ) The contact that causes an allergic reaction could be either on your mouth, stomach, lining of your lungs or your skin. The reaction itself can manifest in a variety of ways from quite mild to serious & sometimes resulting in death.

The symptoms of an allergic reaction include wheezing, sneezing, sinus pain, coughing, runny nose, swelling, developing a rash, itchy lips, throat, palate, eyes, short breath, vomiting & diarrhoea. Typically a person does not suffer an allergic reaction the first time they come into contact with a substance or allergen, this will occur at a later point of contact as the body needs to develop sensitivity before it becomes allergic.

Types Of Allergy Testing

There are four main allergy testing methods, these are blood test; skin prick test; challenge test & patch test.

1. Blood Test – A small sample of your blood is taken & passed to a laboratory for a Radio Allergo Sorbent Test (RAST). This test is able to measure the amount of Immunoglobulin E antibodies which are responsible for triggering the release of histamines within your body. In addition to this test there is also one, which can assess allergies towards specific foods & can drill it down to specific substances such as coconut, hazelnut, peanut, mussel, shrimps etc.

2. Skin Prick Test – For this test a needle pricks the skin (usually the arm, hand or back) through a liquid that contains within it a known allergen. A positive reaction is seen as the area becomes red & itchy with white swelling known as a weal. This usually dissipates within 20 minutes or so. The bigger the weal, the greater your allergy. This test is simple & effective & can test over 350 allergens.

3. Challenge Test – This test is usually carried out in hospital where allergens are introduced to areas of the body such as lung, nose, eye to assess allergic reactions. When looking at food allergies specific foods are introduced in a capsule or broth without the patient knowing which one is being tested – this is known as a double blind placebo controlled food challenge (DBPCF). It should be noted this type of test should only be carried out in specialist allergy units, which have resuscitation equipment on hand.

4. Patch Test – A patch test is used to diagnose delayed allergic reactions e.g. skin rashes. A test is carried out by sticking/ placing a variety of discs to the patients skin each of which have a different allergen embedded on their surfaces. These discs are held in place for up to 48 hours then removed & adverse reactions to the skin assessed by a dermatologist. This type of test is predominantly used to identify allergies to solvents, preservatives, medications, cosmetics, dyes, nickel, rubber etc.

Article Submitted By

David Ibbotson, GoToSee Journalist

Date Published

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