Allergy Testing for Better Asthma Control

B.S. Dietetics, Dietitian, Health Professional

Many people with asthma find that there are things they are allergic to that make controlling their asthma difficult.  That is when it becomes important to identify each asthmatic's specific triggers.  What bothers one person may not bother another.  We know this all too well.  We have twins, both with asthma, and they have very different triggers.  This is when allergy testing comes in handy. If you have asthma and your doctor suggests allergy testing these are some of the tests that you might expect to encounter.

Blood testing

During an allergy blood test patients will have a basic blood draw and the lab will measure levels of the IgE specific to whatever allergen they suspect.  If the test is positive then it is likely that the patient has an allergy to that substance.   Higher levels of IgE do not always indicate that the allergy is worse for that specific allergen and lower levels do not mean the allergy is mild.  History of symptoms has to be used in conjunction with these tests to determine the severity of the allergies.  When in doubt use your symptoms as a guide and avoid any substance that has caused a known reaction.  Blood tests can be more expensive than some of the other allergy testing.  However, many find it beneficial that they do not have to avoid their allergy medications in order to have the testing done.

Skin prick or scratch tests

Skin prick or scratch tests are one way that an allergist can test for a reaction to many different substances.  Multiple drops of an allergen are placed on the skin and the skin is then pricked.  The resulting skin reaction is monitored and assessed to determine which substances the patient is allergic to. The benefit to skin testing is that it is relatively cheap and results are fast.  Patients do have to avoid certain medications like antihistamines for several days before the test.  Check with your allergist for specific instructions.

Intradermal skin testing

Intradermal testing is most often done to test for penicillin or bee venom allergies.  It can also be done when a patient tests negative to skin prick tests but the physician still suspects an allergy.  During this test a small amount of the allergen is injected into the skin.  The resulting reaction is monitored to determine whether an allergy is present.  As with skin prick testing, patients may be advised to avoid certain allergy medications prior to the test.

Patch testing

Patch testing is often used to identify reactions to things touching the skin.  In this form of testing the substances are taped to the skin for 48 hours.  The physician will then look at the skin within 96 hours to asses if there is an allergy present.  Allergy medications have to be avoided prior to this test as well.

Elimination testing

Elimination testing involves complete avoidance of an allergen to determine if symptoms improve.  If symptoms improve the item can be reintroduced to see if symptoms return.  Most of the time people use this as a tool to determine on their own what their allergies might be.  This can be safe with intolerances but for true allergies reintroducing an allergen can be dangerous and even deadly, especially for patients with asthma.  Do not conduct these types of trials without your physician's approval.

There are many benefits to figuring out what allergens trigger your asthma.  Once a person's asthma triggers have been determined those things can be better avoided or eliminated.  Some patients may have specialized allergy shots created to build a tolerance to that allergen and potentially eliminate future reactions.  All of these steps can be essential in providing good asthma control and allowing you to breathe freely again.

_Jennifer has a bachelor's degree in dietetics as well as graduate work in public health and nutrition.  She has worked with families dealing with digestive disease, asthma and food allergies for the past 12 years.  Jennifer also serves the Board of Directors for Pediatric Adolescent Gastroesophageal Reflux Association (PAGER). _

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