Tests for Allergies & Treatments

There are several tests or procedures that are used by physicians to detect allergies. Most of these tests remain controversial.1 Some clinicians (cited below), however, believe some of these tests can be effective.

Scratch testing:

This form of testing is one of the most widely used. A patient’s skin is scratched with a needle that contains a portion of the food, inhalant, or chemical that is being tested. After a period of time, the skin is examined for reactions. If there is a reaction, it is determined that an allergy exists. Although this test is accepted by most allergists, scratch testing is subject to a relatively high incidence of inaccurate results, some tests showing positive when the person is not truly allergic to the substance (false positive) and some tests showing negative when an allergy really exists (false negative).

RAST/MAST/PRIST/ELISA (and other tests that measure immunoglobulins):

(and other tests that measure immunoglobulins): The radioallergosorbent test (RAST) indirectly measures antibodies in the blood that react to specific foods. It is used by many nutritionally oriented physicians and has been shown to be a somewhat reliable indicator of allergies.2 3 It does not, however, pick up nonallergic food sensitivities and is therefore associated with a high risk of false negative readings. In an attempt to avoid this problem, a variety of modifications have been made to tests related to RAST (such as MAST, PRIST, and ELISA). Some of these changes may have reduced the risk of false negative readings somewhat but are likely to have increased the risk of false positive readings. A number of conditions associated with food sensitivities, such as migraine headaches and irritable bowel syndrome, have shown remarkably poor correlation between RAST results and proven sensitivities.

Cytotoxic testing:

The cytotoxic test views a patient’s serum under a microscope to see whether it is reacting to certain substances. The test is subject to numerous errors and is not generally considered to be reliable.4

Clinical ecology  (also called “provocative neutralization” or “end-point titration”): This branch of medicine is considered very controversial. Testing is done using intradermal injections of minute dilutions of foods, inhalants, or (in some cases) chemicals. Based on reactions, additional dilutions are used. This test not only determines whether an allergy exists but also operates on the theory that one dilution can trigger a reaction while another can neutralize a reaction. Preliminary research suggests that this approach may have beneficial effects,5 6 though negative research exist.7

Elimination and reintroduction:

It is universally acknowledged that the most reliable way to determine a food allergy is to have the patient eliminate a suspected food from the diet for a period of time and then reintroduce it at a later date. The theory behind doing this is that once a food is eliminated, the symptoms that food is causing stop. The body then becomes more sensitive to the food, so when it is reintroduced, the symptom is more likely to recur. This tool lets the patient know with a high degree of certainty which foods are problem foods. This sort of testing requires a great deal of patience and, as with all other forms of allergy testing, is best undertaken with the help of a nutritionally oriented physician who can monitor the diet.8 Reintroduction of an allergic food has been reported to lead to occasionally dangerous reactions in some patients with certain conditions—another reason this approach should not be attempted without supervision.

Environmental Allergies:

Some people react to chemicals in the environment. There are chemicals indoors and outdoors, as well as in food, water, medications, cosmetics, perfumes, textiles, and plastics that can trigger allergies. Detecting which chemicals are problems and then eliminating or reducing exposure to them is a time-consuming and challenging task that is difficult to undertake without the assistance of an expert in this area.9 10

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References:
1.. Am Academy of Allergy. Position statements: controversial techniques. J Allergy Clin Immunol 1981:333-8.
2. Gleich G, Yunginger J. The radioallergosorbent test: its present place and likely future in the practice of allergy. Adv Asthma Allergy 1975(Spring):1.
3. Wraith DG. Recognition of food-allergic patients and their allergens by the RAST technique and clinical investigation. Clin Allergy 1979:25-36.
4. Lieberman P, et al. Controlled study of the cytotoxic food test. JAMA 1975:728-30.
5. Miller JB. A double-blind study of food extract injection therapy: a preliminary report. Ann Allerg 1977:185-91.
6. Hosen H. Provocative testing for food allergy diagnosis. J Asthma Res 1976:45-51.
7. Jewett DL, Fein G, Greenberg MH. A double-blind study of symptom provocation to determine food sensitivity. New Engl J Med 1990;323:429-33.
8. Mandell M. Dr. Mandell’s 5-Day Allergy Relief System. Pocket Books, New York, 1979.
9. Zamm AV, Gannon R. Why Your House May Endanger Your Health. Touchstone, New York,1980.
10. Randolph TG. Human Ecology and Susceptibility to the Chemical Environment. Charles C Thomas, Springfield, 1978.

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