New Food Allergy Clinical Advisory to Pediatricians

  Our 2nd [new] allergist believes in doing food challenges, almost as a gold standard for diagnosing food allergies; but my concern is that unless a child is old enough to verbally communicate symptoms, how would itchy throat/mouth, numbness, nausea, diarrhea or many other un-noticeable symptoms be calculated? It also left me wondering about when there are undiagnosed allergies, and trying to discern what the triggers are- an example, my oldest son had food allergies diagnosed to peanuts, tree nuts, and dairy, but still had GI/diarrhea etc issues; a food panel scratch test showed allergic reactions also to: eggs, beef, pork, yeast, canola! Even though he has had documented reactions to dairy, and peanuts, as well as the positive skin test results,  his RAST test ONLY came back with a reaction to peanuts!  [Yes he will be getting a GI scope done soon to check for EoE too, since Jacob has been diagnosed with this].  New guidelines for diagnosing food allergies leaves me with questions~ I know I am not alone at being frustrated with the vague and imperfect allergy tests currently used, but reading this made me want to bang my head against a wall!~So much of diagnosing is open to interpretation, and why it is important to find a good allergist!  I truly hope that more accurate testing methods become available in the future!~
Here is the brief version released from the Johns Hopkins Children’s Center and below is also the link to the publication for Jan 1012 PEDIATRICS~Official Journal of the American Academy of Pediatrics:
Johns Hopkins Children’s Center
December 26, 2011

-New report includes guidelines on whom and when to test

An advisory from two leading allergists, Robert Wood of the Johns Hopkins Children’s Center and Scott Sicherer of Mount Sinai Hospital in New York, urges clinicians to use caution when ordering allergy tests and to avoid making a
diagnosis based solely on test results.

In an article, published in the January issue of Pediatrics, the researchers warn that blood tests, an increasingly popular diagnostic tool in recent years, and skin-prick testing, an older weapon in the allergist’s arsenal, should never be used as stand-alone diagnostic strategies.  These tests, Sicherer and Wood say, should be
used only to confirm suspicion and never to look for allergies in an asymptomatic patient.

Test results, they add, should be interpreted in the context of a patient’s symptoms and medical history. If a food allergy is suspected, Sicherer and Wood advise, the patient should undergo a food challenge — the gold standard for diagnosis — which involves consuming small doses of the suspected allergen under medical supervision.

Unlike food challenges, which directly measure an actual allergic reaction, skin tests and blood tests are proxies that detect the presence of IgE antibodies, immune-system chemicals released in response to allergens. Skin testing involves pricking the skin with small amounts of an allergen and observing if and how the skin reacts. A large hive-like wheal at the injection site signals that the patient’s immune system has created antibodies to the allergen. Blood tests, on the other hand, measure the levels of specific IgE antibodies circulating in the blood.

These tests can tell whether someone is sensitive to a particular substance but cannot reliably predict if a patient will have an actual allergic reaction, nor can they foretell how severe the reaction might be, the scientists say. Many people who have positive skin tests or measurably elevated IgE antibodies do not have allergies,
they caution. For example, past research has found that up to 8 percent of children have a positive skin or blood test for peanut allergies, but only 1 percent of them have clinical symptoms.

“Allergy tests can help a clinician in making a diagnosis but tests by themselves are not diagnostic magic bullets or foolproof predictors of clinical disease,” Wood says. “Many children with positive tests results do not have allergic symptoms and some children with negative test results have allergies.”

Undiagnosed allergies can be dangerous, even fatal, but over-reliance on blood and skin tests can lead to a misdiagnosis, ill-advised food restrictions or unnecessary avoidance of environmental exposures, such as pets.

In addition, the researchers caution, physicians should be careful when comparing results from different tests and laboratories because commercial tests vary in sensitivity. Also, laboratories may interpret tests results differently, making an apples-to-apples comparison challenging, Wood says.

In their report, the scientists say, skin and blood tests can and should be used to:
• Confirm a suspected allergic trigger after observing clinical reactions suggestive of an allergy. For example, children with moderate to severe asthma should be tested for allergies to common household or environmental triggers including pollen, molds, pet dander, cockroach, mice or dust mites.
• Monitor the course of established food allergies via periodic testing. Levels of
antibodies can help determine whether someone is still allergic, and progressively decreasing levels of antibodies can signify allergy resolution or outgrowing the allergy.
• Confirm an allergy to insect venom following a sting that causes anaphylaxis, a life-threatening allergic reaction marked by difficulty breathing, light-headedness, dizziness and hives.
• Determine vaccine allergies (skin tests only)
Conversely, skin and blood tests should NOT be used:
• As general screens to look for allergies in symptom-free children.
• In children with history of allergic reactions to specific foods.  In this case, the test will add no diagnostic value, the experts say.
• To test for drug allergies. Generally, blood and skin tests do not detect antibodies to medications.
Nearly 3 percent of Americans (7.5 million) and at least 6 percent of young children have at least one food allergy, according to the latest estimates from the National Institutes of Health.Related:Warning: Food Allergy Blood Tests Sometimes

LINK to Full Article HERE [Page 2- test selection and interpretation; Page 3 relates specifically to Food Allergy Diagnosis]:
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