Skin Prick Testing is recommended as the primary method of testing allergies.
An allergy is a reaction that is caused by a particular class of antibodies, E antibodies or IgE. By definition saying someone has an allergy means that an E class antibody, IgE, has been made against something causing symptoms to develop. IgE-mediated allergies cause allergic rhinitis (hayfever), allergic conjunctivitis (itchy eyes), asthma, atopic (allergic) dermatitis, and food allergies which can cause anaphylaxis, acute urticaria and angioedema. IgE-mediated allergies also cause allergic reactions to insect venom, wasps, bees, ticks and native Jack Jumper Ants, latex allergy and some drug allergies.
Skin prick testing is valuable because:
- It is relatively sensitive and specific
- It provides rapid results – the result is known 15-20 minutes after the test is done
- It causes minimal discomfort – it is a small scratch and the device used has been designed to minimise the discomfort.
- It is relatively inexpensive and there is a rebate from Medicare for the test
While it is very safe, there is a very small risk of anaphylaxis occurring during the test (less than 2 in 10,000 tests). This means that it should be carried out in an environment where this can be properly treated. In our rooms the testing is done after review with an allergy specialist to identify people at high risk for a severe reaction and advise other test methods where appropriate. Additionally, Dr Falk is there to promptly treat any reactions, and with the high standard of practice we adhere to, the reaction rate is is far less than the standard level of 2 in 10,000 tests.
To properly carry out and interpret Skin Prick Testing, a detailed history is required to ensure the correct tests are performed. Then the practitioner must correctly interpret the results in the light of the history that has been obtained. The tests should not be interpreted without a history and an experienced clinician should always be involved.
Some people can be concerned that the process of skin prick testing can increase the risk of allergy problem to those allergens in the future. There is no scientific evidence that being tested for an allergen will increase the risk of allergy in the future.
The SPT Process
The process of Skin Prick testing consists of the following:
- Oral antihistamines need to be avoided for 3 days before the test because they work by settling any allergy responses and make interpretation of a SPT impossible.
- Detailed history taken by the doctor
- Decision about what specific allergens need to be tested
- The doctor applies a very small drop of the allergen to the skin with a very fine needle that creates a very small prick on the surface of the skin. It is virtually painless.
- The patient waits for 20 – 30 minutes to see if any of the test sites react. During this time, your body will mount an allergic response to any allergens that you are sensitive to.
- The doctor reviews the skin prick test sites and is able to provide you with diagnosis and advice based on the results