Board-certified allergists are specialists who are highly trained to understand the ins and outs of allergy testing and to oversee what happens during and after test sample analysis. These skills are important because there are many variables that affect allergy test results. If these nuances are missed or wrongly interpreted by physicians who do not specialize in allergies and asthma, individuals may not get the best treatment to relieve their symptoms.
Skin tests for allergic disorders have been around since the 1860s. Today, prick or puncture tests are commonly used by allergists as diagnostic aids. These tests are not very invasive and, for most allergens, they tend to produce quick results. If the results of prick or puncture tests are negative, they may be followed by intradermal tests, which give allergists more details about what’s causing the underlying symptoms.
Here is how both types of tests are administered:
- Prick/puncture. A diluted allergen is applied with a prick or a puncture on the surface of the skin.
- Intradermal. Using a 26- to 30-guage (very thin) needle, a diluted allergen is injected immediately below the skin surface.
After either type of test, the area of the skin is observed for about 15 minutes to see if a reaction develops. The “wheal”—a raised, red, itchy bump and surrounding “flare”—indicates the presence of the allergy antibody when the person is exposed to specific allergens. The larger the wheal and flare, the greater the sensitivity.
Although skin testing may seem simple, it must be carried out by trained practitioners with an understanding of the variables and risks of the testing procedure.
Steps should include:
- After reviewing the patient’s medical history and performing a physical exam, the allergist determines that allergy skin testing is both appropriate for the patient and does not put the patient at risk for a bad outcome (such as severe anaphylaxis or an asthma attack in poorly controlled asthma).
- A trained nurse performs the skin testing under the supervision of the allergist.
- The allergist personally “reads” the skin tests and, in evaluating the skin test reactions, discerns several factors that lead to proper interpretation.
These factors include:
- Proper evaluation and selection of which patient may benefit from skin testing
- Condition and reactivity of the skin
- Proper selection of where the skin tests are placed
- Type of skin test placed
- Device used for skin testing
- Proper technique in applying the tests
- Quality and selection of the allergen extracts used
- Medications that could alter the validity of the results
In addition to carefully considering allergy testing variables, board-certified allergists are trained to report test results according to standard practices endorsed by the American College of Allergy, Asthma & Immunology.
Standardized allergy test records are vital since patients often change doctors. When they do, their new allergist must be able to accurately interpret their health records. If information is incomplete, patients may be ordered to undergo additional skin testing that would have been unnecessary had standard practices been followed.
Guidelines suggest that skin test records report the diameter of the wheal and the surrounding “flare” (measured in millimeters) and record information to account for the differences in testing devices. The measurements are usually reported in millimeters of diameter.
Allergy nurses performing allergy and asthma tests are also required to meet basic quality assurance standards to ensure that they are using the proper techniques.
Seeing a board-certified allergist will assure these guidelines are followed. Allergy skin testing is relatively safe; adverse reactions are rare. Even so, researchers recommend that the value of any test be carefully considered before it is administered.
Potential Risks of Non-Specialist Care Include:
- Misinterpretation of test results
- Overprescription of medications and treatments
- Costly and unnecessary allergen avoidance
Source: www.aafa.org, Asthma and Allergy Foundation of America (AAFA)
Allergy skin testing is done to find out exactly what things a person may be allergic to.
With my mom’s help, I kept a record of my allergy symptoms for 2 weeks. I wrote down when I had my symptoms, how long they lasted, where I was, what I was doing and medicines I took for them. My doctor reviewed the record but still couldn’t figure out what I was allergic to. So he referred me to an allergist for skin testing, which showed I was allergic to mold. The next step was to get rid of the mold in our home. — Jamie, age 17
How are skin tests done?
Skin tests are done in an allergist’s office.
There are two types of skin tests:
- Prick or scratch test. In this test, a tiny drop of a possible allergen—something you are allergic to— is pricked or scratched into the skin. (This is also called a percutaneous test.) It is the most common type of skin test.
- Intradermal test. This test shows whether someone is allergic to things such as insect stings and penicillin. A small amount of the possible allergen is injected under the skin through a thin needle.
What is an allergy?
An allergy occurs when you react to things like pollen or cats that don’t affect most people. If you come into contact with something you are allergic to (called an allergen), you may have symptoms such as itching or sneezing. This is called an allergic reaction.
What can I expect during a skin test?
Anywhere from 10 to 50 different allergens are tested. It takes about 5 to 10 minutes to place the allergens on your skin. They are usually put on the forearm in adults and on the back in children. Then you will wait about 15 minutes to see if a small red lump appears where any of the allergens were placed.
The prick or scratch test and intradermal test may hurt slightly. If you are sensitive to any of the allergens, your skin may itch where the allergen was placed.
How should I prepare for the test?
- Tell your allergist about all medicines you’re taking, including over-the-counter medicines.
- Don’t take antihistamines for 3 to 7 days before the test. Ask your allergist when to stop taking them. (It’s okay to use nose (nasal) steroid sprays and asthma medicines. They will not interfere with skin tests.)
Is the test safe?
Very small amounts of allergens are tested on your skin, so skin testing is safe. During the test, the allergist will watch for a possible severe allergic reaction, but it rarely happens.
What do the skin test results mean?
If you’re sensitive to an allergen:
- With the prick or scratch test and intradermal test, a small red bump appears on the skin where that allergen was placed, and this area may itch. The larger the bump, the more sensitive you may be to it.
These results are called positive skin tests and mean that you may be allergic to the allergen tested.
Even if a skin test shows that you’re allergic to something, you may not react to it when you’re exposed to it later. Your allergist will review your medical history and skin test results to help find out what you’re allergic to.
What happens if the skin test shows I have allergies?
Your allergist will create a plan for controlling your allergies. This means preventing and treating symptoms. Take these steps:
- Avoid or limit contact with your allergens. For example, if you’re allergic to dust mites, reduce the clutter in your house, which collects dust.
- Take medicine to relieve your symptoms. Your allergist may prescribe medicines such as antihistamines, decongestants, nose (nasal) sprays, or eye drops.
- Get allergy shots if the allergist says you should. Some people need them when they can’t avoid an allergen. The shots contain a tiny but increasing amount of the allergen you’re sensitive to. Over time, your body becomes used to the allergen and no longer reacts to it.
Who does skin testing to diagnose allergies?
Allergists are experts who test for, diagnose and treat allergies.
Does health insurance cover skin testing for allergies?
Most health insurance plans cover allergy testing and treatment. Ask your insurance carrier:
- Do I need a referral from my doctor to see an allergist?
- Does my insurance cover patient education or special services for my allergies?
- Does my insurance cover a pre-existing health problem? This usually means any health problem that you had before you joined your current health plan.
- What allergy testing and medicines does my plan cover?