HOW ARE ALLERGIES DIAGNOSED?
How to Diagnose Allergies: The Physician’s Role
Obviously, there are symptoms we associate with allergies, such as sneezing, runny nose, and watery eyes. The physician recognizes these symptoms as the first clues in how to a diagnose allergies.
However, it must be emphasized that other medical problems can cause these same symptoms. This is why it is vitally important to visit your physician to ensure a correct diagnosis, so that treatment can be effective.
The role of the physician in correctly diagnosing an allergy is similar to a Sherlock Holmes approach: a lot of meticulous detective work.
Once the doctor knows your symptoms, he or she will ask a lot of questions to find out the “when, where, how, and what” of the allergy.
For example, if you start sneezing and wheezing when the furnace kicks on during the summer months, there’s a good chance you are allergic to house dust. I
f you suddenly start developing watery eyes and sneezing on the arrival of a kitten for your daughter, it is likely that you have developed an allergy to cats, or at least, to cat dander.
Many physicians have their own questionnaire for their patients to complete, so that they can systematically evaluate all of the possibilities.
In addition to the dialogue, completion of a questionnaire, and analysis of symptoms, the physician has some precise and objective ways of confirming the “detective work.”
This is one of the most useful tests for physicians. Drops containing a potential allergen (eg, house dust, pollen, mold, or whatever) are placed on the back or forearm. The skin is pricked with a needle, allowing the allergen to enter the skin. This is called a prick test.
A similar technique called a scratch test involves making a superficial scratch on the skin and dropping the allergen onto the scratch. In both cases, an area of redness with swelling will develop if the person is allergic to the particular substance.
The reaction usually occurs in about 15 minutes. If the reaction is severe, the allergen is wiped off the skin.
The intensity of the reaction to the allergen indicates how allergic one is to a substance. These results are used by the physician to confirm the diagnosis.
It is possible to have a reaction to a certain allergen but not be clinically allergic to it; this means one may not have symptoms when exposed to the substance.
Blood Tests: A new way to test for allergies
Besides the skin testing, there is a second type of diagnostic testing for allergies which is done on a blood sample. Blood tests are analyzed in the laboratory and are therefore called “in vitro” (in glass) testing.
Although over 400 specific allergens can be tested from blood samples, the physician decides which should be tested using medical devices in which a complete panel test is performed. The panel, or chamber, consists of 36 preselected allergens common to a specific region.
“Measured” is the key word because this scientific laboratory technique can actually determine, as accurately and precisely as a temperature reading or basketball score, your sensitivity to ragweed, Timothy grass, birch tree pollen or the scallops you may eat.
You may wonder how blood can provide such accurate information about such a simple bodily activity as sneezing when you are exposed to your favorite pollen species from the field next door.
The answer lies in the body’s highly developed immune system as explained here.
Understanding The Allergic “Keys”
An allergic person “overreacts” to pollen, dust, etc. and creates more antibodies (these are protein fighters that destroy or neutralize anything foreign that enters the body) in the blood than somebody who’s not allergic.
If you look upon each allergen as a key—a ragweed key, a house dust key, a cat dander key, a birch tree key—you will see that they are all allergens, but each has a different shape, a different configuration.
The miracle of the body’s defensive (immune) system is that the blood makes “locks” (antibodies) which can be matched to the “key” allergens.
Laboratories can measure the amount of specific antibody for each allergen present in the blood. This tells your physician exactly how much your body has “overreacted” to each of the specific allergens, from the mold in your bathroom to the dust in your vacuum cleaner.
The name for the allergic antibody is IgE. You’ll see this name on your chart and your physician may refer to it. It’s just an abbreviation of a complicated technical name. The test that pinpoints which actual allergen could be causing you the problem is the MAST test.
The reality is that hardly anybody is allergic to just one allergen. Therefore, a successful remedy depends on the ability to identify as many of your allergies as possible.
This is especially true of the physician’s treatment involves “allergy shots” or the avoidance of allergens in your environment, as described in this book.
Physicians use their clinical judgment to choose either skin testing or the blood test to diagnose each patient’s allergies—your safety is their primary concern.Your physician can explain about the availability, price, and merits of this procedure as it applies to you in your area.
In conclusion, you have to appreciate that the accurate diagnosis of your allergic condition is very important for planning your most effective treatment plan. The only person that can do this is the physician, by reviewing not just the skin test or blood test, but your entire case history.
Drugs can mask symptoms, improvements in the home environment can provide some relief, and allergy shots can help if they catch some of the allergens. Remember, “If you don’t know what’s wrong, how can you fix it?”
You are probably beginning to suspect that allergies can be a complicated matter and you are absolutely right. So, let’s move on. Next we’ll discuss how physicians treat allergies.