By Dr. Ehrlich
Nothing separates “science” from sound medical practice more than the use and misuse of allergy testing. Inappropriate testing leads doctors and their patients down blind alleys and dead ends, wasting time, money, and health. More times than I care to remember a new patient arrives in my office like the one this past week, a twenty-three year old man with eczema who recently moved from Florida to New York City. He told me that he is allergic to some twenty foods from milk to asparagus.
His history included some laboratory results of tests that were performed while he was living in West Palm Beach and he said that his physician advised him to stay away from all these foods. His diet was thus reduced to a narrow spectrum that was making his life miserable and his eczema no better.
With the patient in front of me I called the 800 number of the lab and spoke with a woman about the tests. The first thing she wanted to know was what state I was calling from. When I told her I was from New York, she told me that their lab work would not be covered by my patient’s insurance company. (My patient paid cash up front but this shows where their priorities lie.) I then asked her about the tests performed, and she told me they were IgG4 tests to the various foods. I thanked her for the information, hung up and looked at the young man.
“The tests they performed were phonies, with no redeeming clinical significance,” I said without hesitation. “They only tell me only that you have eaten these foods in the past. You’re probably not allergic to any.”
The remainder of the visit included tests related to IgE antibodies, the ones that count, to various foods as well as a few environmental allergens, and they were all negative, suggesting that he could begin all the foods he had eliminated from his diet. Needless to say, he was thrilled. It turned out his eczema came from exposure to dust mites. The history was obvious to an allergist, which his Florida doctor was not, and in fact had never bothered to take a history. Between his insurance company and his own pocket, the Florida office visit and the tests probably involved an outlay three times what it cost at an allergist (yours truly) with nothing to show it. A patient’s history is everything and the tests performed done usually to substantiate what a trained doctor usually suspects.
A final thought: this kind of misdiagnosis of food allergy is bad enough in an otherwise healthy 23-year old. It’s quite another in very small children. I regularly see very small kids whose diets are needlessly circumscribed for the same bogus reasons who are in fact being malnourished. This falls under the antiseptic but loaded heading “failure to thrive.” [For more on food allergy, see chapter 5 Asthma Allergies Children: A Parent’s Guide.]