Food Allergies Diagnostic

The path from the point at which you feel ill to the point at which you receive a diagnosis and treatment plan can be a long and winding road. To assist you in navigating that path, check out this eye-in-the-sky overview of the diagnostic process:

  1. Your general practitioner (GP) performs a physical exam and jots down your medical history. The history is critical in ruling out other possibilities, identifying the likely problem foods, determining which tests are most appropriate, and guiding the interpretation of test results.
  1. Your GP refers you to an allergist. An allergist, particularly one with experience in diagnosing and treating food allergies, can perform additional tests and is usually more qualified to interpret the test results.
  1. Your allergist performs a complete food allergy workup. Like your GP, your allergist is likely to perform a physical exam and take additional notes about your medical history. Your allergist is likely to perform several tests to identify the problem food(s) and rule out suspects that are not involved:
  • Skin tests: Skin testing is used only in the diagnosis of IgE-mediated food allergies — allergies in which your immune system produces IgE antibodies to a specific food. An allergy specialist (rather than your GP) should perform the tests, because of both the risk of anaphylaxis and the skill required to properly interpret the results.

A positive skin test to a particular food indicates only the possibility that you’re allergic to that food. Your allergist may need to perform additional tests to confirm that eating the food causes you to react. In contrast, a negative skin is about 90 percent accurate in determining that you’re not allergic to the tested food.

  • RASTs: Short for radioallergosorbent tests, RASTs look for the presence of food-specific IgE in the blood. These tests are widely available and are unaffected by the presence of medications. In at least one study, RASTs have proven very effective in diagnosing several of the major food allergies in children.

RAST results show the concentration of IgE in the blood, and we have established RAST levels that can predict with about 95 percent accuracy whether a child is allergic to egg, milk, peanut, tree nut, or fish. A child with a test result exceeding the established value, in combination with a positive skin test, does not require food challenge for definitive diagnosis.

  • Food diary: Your allergist may ask you to keep a food diary listing the foods you eat and drink and recording any reactions to those foods. A food diary can be useful in identifying overlooked foods, hidden ingredients, and patterns of reactions.
  • Diagnostic elimination diet: Your allergist may order you to stop eating one or more foods to see if symptoms disappear, which would identify the problem foods. The allergist needs to pay careful attention to nutrition whenever removing an essential food from the diet of a growing child.
  • Food challenges: A food challenge consists of eating the problem food under your allergist’s supervision. Results of a food challenge provide the most definitive data for diagnosing a food allergy. Your allergist will select foods for testing based on the history and the results of skin and/or RASTs.

    Only a qualified allergist who’s familiar with food-allergy reactions and is equipped with the necessary emergency medications should perform a food challenge.

  1. Your GP and allergist may order additional tests if symptoms persist. You may have a non-IgE mediated food allergy or you may have a food intolerance.

The journey from problem to solution often requires time, patience, and persistence. Don’t try to take a shortcut by reaching for untested, unproven alternative tests and treatments.

Funny thing about people in general (specifically men) — they don’t like going to the doctor. They often prefer to tough it out, hope it goes away, or convince themselves that the doctor “can’t do anything” rather than seek immediate medical care. With food allergies, however, avoiding the doctor can be dangerous, because the longer you tough it out without an accurate diagnosis, the more likely your reactions are going to increase both in frequency and severity.

Allergic reactions begin and intensify with increased exposure to allergenic foods. Early diagnosis and an effective treatment plan can not only make you feel better now but also prevent you from feeling much worse down the road. If you or a loved one is experiencing mysterious symptoms, particularly a couple minutes to a couple hours after consuming food or beverages, you may have a food allergy. Complete the self-screening test, shown in Figure below.

This self-screening test serves three very important purposes:

  • Assists you in deciding whether you need to see your doctor or allergist. (If you have any doubt after completing the test, see your doctor anyway.)
  • Provides you with a log of symptoms and other concrete details that you can present to your doctor or allergist, which may be key to an accurate and early diagnosis.
  • Hones your observation and record-keeping skills, which are two of the most valuable skills for any person who has a food allergy or is caring for someone with a food allergy.

This self-screening test is not a self-diagnosis. Identifying specific allergens is tricky, even for a well-trained and experienced allergist, and you may be allergic to multiple foods. In addition, other conditions can produce symptoms similar to those of allergic reactions. Use the self-screening test only as a tool to facilitate a professional medical diagnosis and treatment.

When you first suspect that you have any health problem, the first doctor you typically go to see is a general practitioner (GP for short) — your family physician, pediatrician, or internist. In the case of food allergy, seeing your GP first is a good idea for several reasons:

  • Your GP possesses a breadth of knowledge and training that’s often useful in identifying not only food allergies, but also other conditions that may produce similar symptoms.
  • The GP can coordinate the oversight and management of all your healthcare needs, not only your concerns about allergies.
  • Your GP often has access to your entire health history and may be able to spot patterns in your family history that make certain conditions more likely than others.
  • Your health insurance may require you to see your “primary care physician” (your GP) before approving your visit to a specialist.
  • Your GP can refer you to a qualified food allergist, often one that’s in the same insurance network and perhaps in the same office complex.

Some GPs know quite a bit about food allergies. Pediatricians may even know a bit more, because food allergy is most common in young children. So what’s your GP supposed to do? In the following sections, I describe the standard care you can expect from your GP. If you’re not receiving a standard level of care, express your expectations to your GP. If you’re still not satisfied, you may need to look for another doctor.

Most patients love their GP’s and are satisfied with the general care they provide, but the number one complaint I hear from patients is this: “How could my doctor (pediatricians included) have been so ignorant about food allergy?” Many patients report symptoms of food allergy to their GP’s for years before their GP’s take the reports seriously. (GP’s generally take reports of severe reactions seriously and refer patients to an allergist immediately, but they frequently miss the signs of more subtle reactions.)

The least your GP should do is ask you a lot of questions, record a detailed history of symptoms and what makes them better or worse, and determine the likelihood that you’re at risk for severe or life-threatening reactions — that is, whether you may have an IgE-mediated allergy. If your doctor suspects that you have an IgE-mediated allergy, she will likely take the following steps:

  • Identify suspected food(s) to avoid until you can get in to see the allergist.
  • Refer you to an allergist.
  • Hand you a prescription for autoinjector, such as an EpiPen or Twinject, as a precaution in the event that you experience a future anaphylactic reaction.

To err on the side of safety, assume that the next reaction is going to be more severe than the previous reaction and equip yourself to deal with it. Just because a child developed hives only on her face during her first reaction to milk or egg, you can’t assume that the next reaction is going to be of a comparable intensity.

Your GP may or may not decide to initiate allergy testing. Very few GP’s have the training or materials to perform skin tests, but any doctor can perform blood testing for allergies. RAST (radioallergosorbent test) results can be very helpful in proving that the suspect food really triggered your reaction. However, searching for culprit foods with extensive panels of tests — that is, by ordering tests for hundreds of foods — is usually a huge waste of time and money and risks returning a number of false positive tests which only complicates the diagnosis.

If your doctor doesn’t suspect an IgE-mediated allergy, then she should attempt to determine whether the reaction represented some other type of food allergy or a nonallergic food reaction. The diagnosis and management of non-IgE-mediated food allergy often requires the assistance of a gastroenterologist as well as an allergist.

In some cases, the history may be insufficient for discerning the cause of a particular reaction. This is most often the case with patients who have isolated gastrointestinal symptoms. In such instances, your GP should arrange for further evaluation and proceed as if the reaction were IgE-mediated, including equipping you with epinephrine if suspicion is sufficiently high.

Based on your history and any test results, your GP should tell you which foods to avoid until further evaluation. Your doctor should carefully interpret the RASTs, since you can often test positive for safe foods, and you don’t want to be saddled with an overly restrictive diet. In some cases, a GP orders RASTs but is not fully competent in interpreting the results.

Have your RAST results forwarded to the allergist you decide to see. When you’re on an extremely restrictive diet, meeting your nutritional needs can be tough, especially for infants and children. If your doctor prescribes extreme restrictions, he’s likely to refer you to a nutritionist, as well. If he doesn’t refer you, request a referral.

You visited your GP, she took a detailed history, told you that you probably were suffering from a food allergy, and referred you to an allergist. Good for you. If, on the other hand, your GP offers no reasonable alternative diagnosis or effective treatment and is reluctant to refer you to an allergist, you may have to crank your efforts up a notch:

  • Ask your GP if she thinks the symptoms could be symptoms of food allergy. Sometimes, this is enough to lead a GP on the right path.
  • State the reasons why you suspect food allergy. Use your powers of persuasion to convince your GP that food allergy is a possibility and that a specialist can help confirm your suspicions or rule them out.
  • Request a referral. If your insurance plan requires a written referral from your GP in order to cover your visit to a specialist, your goal is to walk out of your doctor’s office with a referral. Don’t be shy, and don’t take no for an answer.
  • Call your insurance company. Look on the back of your insurance card for a toll-free number. Following are some guidelines and talking points:
  • Always write down the name of the insurance company’s representative you talked with, the date and time, and specifically what the person told you.
  • Ask if your policy requires referrals (some don’t). You may be able to see an allergist without your GP’s referral. If your plan doesn’t require a referral, the cost of seeing an allergist is typically the same as it would be if you had a referral; you’d have to make a co-pay out of pocket.
  • Ask what happens if you see an allergist without a referral or one who’s not in the insurance company’s network. Your policy may not cover out-of-network doctors or cover a lower percentage of the cost than if you were to see an in-network specialist with a referral from your GP.
  • See a food allergist without your doctor’s referral or your insurance company’s approval. This is usually the most costly option, because your insurance company may not pay any of the cost.

If you have to pay out of pocket for tests and treatments, mention this to your doctor. Doctors are human beings who are well aware of the high-cost of medical care. They may offer you a discount or be willing to set up a reasonable payment plan and will often be willing to charge you what they would normally get back from the insurance company (an average of a 36 percent discount).

GPs often have the mistaken notion that allergists can’t perform allergy tests on children until they’re two or three years old. This is clearly wrong. The consensus of food allergists is that the GP should make the referral as soon as possible after concerns of food allergy arise, even in a two or three month old.

The medical community has plenty of evidence that early diagnosis and treatment greatly benefit children and their families. Alternative therapies for food allergies abound. Chiropractors, nutritionists, acupuncturists, and a variety of other alternative practitioners claim the ability to diagnose and treat food allergies.

Some of these healthcare providers may even be quite knowledgeable about food allergies and beneficial in your care. Other practitioners who are more on the fringe or way out there, tout their snake-oils, magic potions, crystals, and other treatments that range from entertaining diversions to dangerous delusions.

Don’t fall for pumped-up promises of miracle cures. Seek well-trained, qualified medical practitioners to diagnose and manage your food allergies. If you do decide to pursue alternative routes — a chiropractor with an interest in food allergy, for example — I always advise that you see a traditional allergist as well.