Diagnosing Hay Fever with Skin Scratch Tests
Itchiness and irritation of the skin is one of the primary side effects of hay fever. Therefore, it is no surprise that skin tests are used as a significant source of information when diagnosing hay fever and other allergies. Skin testing is also known as "puncture testing" and "prick testing" due to the succession of minuscule puncture or pricks made into the patient's skin.
Basically, skin testing is used to identify the main substance causing the allergy, or the allergen. Once you know what your particular allergen is, you can start taking effective measures to avoid it, minimize the symptoms and get on with enjoying summer.
The Process
- A minute quantity of the alleged allergy substance (pollen, grass, mite protein, peanut extract, etc.) is placed on the skin. Common areas for testing include the inside forearm and the back.
- The skin is then lightly scratched through the small drop with a special sterile needle. This is known as the prick-puncture method and is typically used for primary diagnosis. Another method, known as the intra-dermal method, involves injection of a small amount of the test substance into the skin. Intra-dermal testing is more sensitive but also tends to lead to more false-positive results.
- If the skin reddens and, more importantly, swells, then an individual is said to be "sensitized" to the particular allergen. If classic symptoms occur when a sensitized individual is exposed to the assumed substance, then allergy to that substance is probable.
Skin prick tests are not utilized with patients who have severe allergy conditions. This is due to the fact that bringing possible allergens into immediate contact with the patient’s blood could trigger an intense allergic attack. Fortunately, hay fever is usually irritating only, and not critical. Most patients will be subjected to the prick test, unless they have really bad cases of food allergy.
Misleading Results
The main problem with skin prick tests is that some people experience a ‘false positive.’ In other words, your skin might get red and itchy after the test even though you’re not actually allergic to the pollen. For this reason, skin prick tests are usually carried out in combination with other tests.
Extra Information
- Interpretation of the results of the skin prick test is normally done by allergists on a scale of severity, with +/- meaning borderline reactivity, and 4+ being a large reaction.
- Skin testing is preferred over blood allergy tests because it is more sensitive and specific, simpler to use, and less expensive.
- The skin testing method described above is tolerated by the youngest patients and this should be the standard of testing.
I didn't know that the Croc Hunter had hay fever! So sad he is gone, he was an inspiration 
