Allergy Testing

Testing can be done several ways: by injecting things under the skin, by eating things, or by putting drops of extract under the tongue. Each method has advantages and disadvantages; none is perfect.

I. In vivo testing - testing the individual person.
This is the best option because it tests the person with individual substances.

A. Intradermal (needles)

The first thing we do is to inject a little saline just under the skin, and in an adjacent spot, a dilution of the histamine. The saline is the "negative control" and the histamine is the "positive control." We expect that where we inject the histamine, it will be reactive. Reactive means that the wheal – a tiny hive – grows.

Then with the controls in place, we begin to test with foods, chemicals, molds, pollens – whatever allergic substances you are looking for. If the wheal grows, it means you are allergic to those substances. Sometimes you get growth of a wheal and presentation of symptoms (sneezing, itching, brain fog, stomach ache, mood change...). Sometimes people don't get a wheal, just symptoms.

When you react to a substance, we lessen the concentration and vice versa. It confirms the allergy, and determines the dilution of antigen that will work for you.

Antigens operate on approximately the same principal as a homeopathic remedy. If a large amount of something makes you sick, a tiny amount of the same substance reverses the symptoms. The antigen is a small enough amount that the body can let go of the histamine response. Over time, you take progressively larger doses of the substance until the body no longer reacts.

It may take several months or several years of consistent treatment until the body no longer reacts. Shots may be daily or twice a day at the beginning. For some people, once or twice a month is all they need. The reaction tells us.

B. Sublingual (under the tongue)

Sublingual testing operates in much the same way but you don't see a wheal. When you put drops under the tongue, the liquid goes into the lymphoid tissue. The sublingual method relies entirely on provoking symptoms. Within 10 minutes, symptoms will appear if you are allergic to the substance being tested.

Injections give you something objective to measure. Many people prefer them because they may be able to bypass provoking the symptoms.

However, kids especially are skittish about needles, even tiny needles that don't go in very far.

Sublingual testing is also called the Provocation/Neutralization testing. The major disadvantage of this method is that we can only test a few substances at each visit. This testing is described in detail in a book by Doris Rapp, MD entitled "Is This Your Child?"

We look for reactions to allergy-causing substances

Testing can done sublingually, using drops of antigen under the tongue, or with individual injections under the skin

We wait 10 minutes for a reaction. Reactions can be neutralized with dilutions of the offending allergen, given to the patient in the form of neutralizing drops.

The Elimination Diet is the gold standard of all food allergy testing. It is 100% accurate. Unfortunately it is also very difficult to do successfully, since it requires severe dietary restriction. A different food is eaten at each meal, four meals per day. The diet takes 3 weeks to accomplish, and obviously requires rigid control over the food intake. It is not realistic to test chemicals, colorings, molds, inhalants, biologicals or additives with this method.

A. Cytotoxic – ALCAT or Sage
The ALCAT and SAGE tests are blood tests, about 86% accurate compared to the elimination diet. We find this test very useful in the diagnosis of food, mold or chemical/additive/colorings allergies. We can test more than 100 foods, as well as molds, colorings, additives and chemicals with a single blood test. The disadvantage of this test is that the list of positive reactions tends to be long, and once again there is no way to correlate a positive reaction with a specific symptom. However, the test does give us a place to start, in determining the body's reactivity to the outside world. This test would be chosen for those patients who cannot take the time to do more specific testing, or who live far away from the office and who at least want a place to start in their search for what is causing their symptoms.

B. IgG immunoglobulin
An immunoglobulins test is done to measure the level of immunoglobulins, also known as antibodies, in your blood. Their presence is thought to represent a manifestation of food intolerance in some people. There is no correlation of IgG level with specific symptoms, so once again, the only way to know whether a food is actually causing problems is to eliminate it from the diet.

C. IgE immunoglobulin (RAST testing for immunoglobulin to specific substances)
IgE is a protein produced in the blood in response to a foreign invader. IgE immunoglobulins are measured by any standard laboratory. This test only measures immediate hypersensitivity responses which can result in reactions like hives or anaphylactic shock. Food and chemical sensitivities may be delayed reactions, and may not have an IgE component, or may not be mediated through immunoglobulins at all.

IV. Skin testing
Done by injecting a small amount of antigen (food, pollen, etc) under the skin and observing for reactions. If there is significant swelling and redness (wheal and flare), then the test is considered positive. If there is no significant reaction, the test is considered negative. This form of testing is used in the typical allergist's office.

A. Standard skin test
Utilizes injection of a standard dose of antigen, which will not cause a serious allergic reaction in 95% of people. The disadvantage of this type of testing is that it can cause a serious or even fatal allergic reaction in the other 5%, those people who are especially sensitive. It's a one-size-fits all standard dose; the dilution may be too weak to provoke a reaction in someone only mildly sensitive to it.

B. Prick test
Utilizes a needle-studded board which is dipped into allergens and pressed into the skin of a person's back. This form is rapid and very easy to do. The disadvantage is that it is also relatively inaccurate, because there is no control over the dose of antigen, and so it is possible to miss a reaction because of inadequate dosage.

At the Arizona Center for Advanced Medicine, we sometimes use the ALCAT for people who live far from the clinic, or for people who simply cannot schedule the time required for more specific testing. We use in vivo testing as our major tests for food, inhalant and chemical allergies because we find them to be the most accurate, reproducible, and clinically useful tests.

We schedule allergy testing in 4 hour blocks of time, however for very young children, we may only schedule 2-hour blocks. Multiple sessions may be needed, depending upon how many things are tested and also depending on the individual's reactivity.

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