Allergy Testing


 Allergy Testing - Physician Overview
 Allergen Test Requisition (ON | BC)
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Note: This test must not be used in isolation to determine whether the patient has outgrown a food allergy. More...

Test at a Glance

Assay: Allergy Serum Test

Diagnosis and Monitoring for Allergies

Clinical Application
Our bodies come into contact with allergic triggers through the air we breathe, the foods we eat, and the things we touch. As a result, allergic reactions may occur in any part of the body. Allergy attacks may occur immediately after exposure to an allergen or several days later. An allergic reaction can range in severity from mild to a life-threatening medical emergency (anaphylaxis).

Specific Sample Requirements
Unlike the traditional "skin testing" method for allergies, this test requires only a simple blood sample (5 mls or one teaspoon).

Turnaround Time: 7-10 working days from time of collection.

Advantages of Assay
Can be used as an adjunct to skin testing and is recommended as an alternative in many clinical circumstances. The clinical sensitivity and specificity is in the range of 90% for most allergens tested and seems to be particularly useful in identifying food allergens.

Additional Information:

Allergic Symptoms

The most commonly affected areas are:

  • The eyes-where itching, redness, and tearing may occur. Dark circles that form under the eyes are a sign of allergies known as "allergic shiners."
  • The nose-where an itchy, runny, stuffy nose, and excessive sneezing are symptoms of allergic rhinitis or "hay fever."
  • The lungs-where shortness of breath, wheezing and chest tightness are symptoms of asthma.
  • The digestive tract-where stomach cramps, bloating, vomiting, and diarrhea may result from food allergies.
  • The skin-where allergic reactions to foods, medicines, household chemicals, plants, or insect stings may cause itchy rashes or patches of swelling or red blotch known as hives.
Allergy attacks may occur immediately after exposure to an allergen or several days later. An allergic reaction can range in severity from mild to a life-threatening medical emergency (anaphylaxis). It is important to know what is causing your allergies.

Allergic Response
Our body's immune system helps keep us healthy by producing disease-fighting antibodies. These antibodies are capable of destroying harmful foreign substances like viruses and bacteria that causes disease. In people with allergies, these antibodies are over stimulated and react to normally harmless substances. Substances that can cause allergic reactions are called allergens. Common allergens are pollens, moulds, household dusts, house pets, or foods. When people with allergies are exposed to them, the body launches a full-scale attack by producing large amounts of an antibody called immunoglobulin E, or IgE. These IgE antibodies cause the majority of allergic reactions.

Allergy Facts
More than 9 million Canadians suffer from some form of allergy. Some allergies come and go with the seasons, while others last year round. Most allergies develop during infancy or childhood, but new allergies may appear at any age. Children who have an allergic parent are more likely to develop allergies, but will not necessarily develop the same allergies as their parents. Some childhood allergies may eventually disappear. However, some people with milk allergies during their early years may suffer more severe reactions later in life.

Common Allergies
The most common allergens are pollens, mould spores, dust mites, animal danders, certain foods, medicines, and insect stings. Many other factors that are not considered allergens can also bring on heightened allergy symptoms. These include weather conditions, such as sunlight, humidity, heat or cold; and irritants, such as cigarette smoke, paint fumes, solvents, and perfumes. Since allergic reactions can mirror cold and flu symptoms, people often mistake one condition for the other. Testing a person's blood can be useful in distinguishing between true allergic reactions and other non-allergic caused symptoms.

Diagnosis of Allergies
A detailed clinical history including environmental and living habits is the most important first step in identifying allergic symptoms and what might be causing them (allergens). The next step to confirm your physician's impression is to employ a skin test or our new allergy service (blood test).

Skin Tests
Suspected allergens in a dilute solution are applied to the skin, and a needle is pricked in the skin through the small drop of fluid. The appearance of a raised welt (weal or hive) or irritation indicates a sensitivity to the allergen. The size of the welt may also indicate the severity of the reaction.

The skin test is not appropriate if you have an allergic skin disease and is less effective in infants and older adults (> 60 years). The results may also be affected by medication.

Serum Test - "UniCAP®" The new test requires a small sample of blood (5 mls or one teaspoon) from which serum is obtained after the blood has clotted. The serum is tested for the presence of IgE antibodies for a mixture of allergens e.g., a panel of grasses, or a panel of trees depending upon the physician's suspected diagnosis. If the result is positive, then a further test can be done on the same sample to determine exactly which type of grass or tree is causing the allergic reaction.

The test result is not affected by medications and in fact can be used to monitor the benefit of therapeutic approaches to your allergies.

Talk to your doctor and see if this test is appropriate for you. It isn't complicated. All that is required is a simple blood test.

The new blood test for allergy testing may or may not be covered by your provincial health plan or by your private insurance plan. If testing is not covered, you will be charged at the time of specimen collection. Any additional allergen tests ordered, after the initial test, will also be billed to you.

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