It’s a topic of conversation everywhere – schools, playgrounds, workplaces and cafés. That just reflects the scale of the problem. At present, 1 in 5 Australians is affected by an allergy, of which food allergies constitute the majority. Australia has among the highest rate of food allergies in the world. Government statistics from 2012 claim that a whopping 17% (or 3.4 million) of Australians had dietary restrictions. In 2016 that number has only risen.
A more disturbing trend shows that hospital admissions for anaphylaxis have gone up 4 fold while deaths due to allergies are rising by 10 percent a year. With allergies emerging as a serious public health issue, in 2015, a National Allergy Strategy was developed. The idea was to have a coordinated plan to manage allergies in Australia.
But before allergies can be effectively managed, the triggers (allergens) need to be accurately identified and the intensity of reaction monitored. This can involve a long and sometimes frustrating testing process for patients and their carers.
But first what is an allergy?
Simply put, allergy testing is the procedure used to determine which particular substance (could be food, pollen, dust mites, chemicals, medical drugs, etc.) is responsible for triggering an allergic reaction. An allergic reaction happens when the body seeks to protect itself from what it thinks is an ‘invader’. The immune system overreacts and typical symptoms involve a localised rash, breathing difficulties, itchy and red eyes, face bumps or hives (whole body rash). A very severe reaction is anaphylaxis and has the potential to be fatal.
Often with the first allergic reaction, it is very hard to identify the allergen. Also, a person may be allergic to more than one substance. Allergy testing is, therefore, the best way to start.
The GP is your first port of call
Before starting on the test procedure, it is important to have some information on hand. So a good place to start is with your GP. Some of the things to discuss would be:
- Discuss your medical history: If you’ve been with your GP for some time, the records will contain enough information. If not, you may need to transfer records from previous GP’s so that all your records are complete and in one file.
- Your genetic history: Walk through your genetic history with your GP. Provide information on conditions and illnesses your parents or family have had. Often genetic history can provide vital clues in identifying causes.
- Let your GP know as precisely as possible the symptoms, the severity and time and place when they occur. If you know what you ate just before the allergy struck, let your GP know.
- List out all the medications you may currently be taking. Your GP will inform you if any of these could interfere with the testing.
Types of allergy testing
Allergy testing has a few different procedures. It is vital that the testing is done by a qualified medical professional. Given how widespread allergies are, a lot of hospitals are staffed with allergy testing specialists and highly qualified immunologists. So make sure that with the help of your GP you go to the right person. Based on the symptoms you have provided the specialist will make a list of allergens to be tested for.
The skin prick test: This method is considered the primary method of diagnoses for most allergens, but particularly for low-risk cases where systemic allergic reactions have been observed. One allergen at a time is applied to the forearm or back before the skin is pricked.
The prick enables a small amount of purified allergen to penetrate. If the patient is allergic to the substance, there will be a reaction within 20 minutes. Testing for cases where there is a risk of anaphylaxis is conducted by specialists in medical facilities that can treat a reaction swiftly.
Specified IgE blood tests: These tests are recommended by the GP when skin testing is not possible or inconclusive. This test establishes the level of IgE (which is a group of antibodies) in the blood. The results indicate to the specialist which allergen is the culprit. If IgE antibodies to particularly food are present in the blood, there is a high likelihood of the person being allergic to that food.
Patch testing: This form of testing is commonly used to diagnose contact dermatitis. People are often allergic to certain perfumes, metals and sometimes plants (poison ivy gets its name for a reason). When a patch containing the substance is applied to the skin, a positive result will show as a blister or rash under the patch.
Elimination diets and challenge testing: Most of the time people have a pretty good idea of foods that cause their allergic reaction. This test helps confirm that hunch. It’s a long test and can take weeks. In the initial stages of the test the person only consumes foods not suspected to be allergens. Then there is a ‘challenge’ – from a food suspected to be an allergen. If the person can tolerate small doses, larger ones are introduced till the food is eliminated as a possible allergen. This process continues till an allergic reaction occurs, identifying the offender. Again this is a test that should be performed only by specialists and in medical facilities that can treat an allergic reaction if one occurs.
Often one test cannot conclusively diagnose an allergen and a combination of tests may need to be conducted for certainty. A good team comprising your GP, allergist and/or a qualified immunologist should be able to diagnose your allergy and prepare an action plan to help you manage it. The combination of accurate testing, a good action plan and regular review is the secret to successfully managing allergies.
