Grayson Grebe started getting eczema on his cheeks when he was just 4-weeks-old. At 6 months, he was diagnosed with allergies to wheat, dairy, eggs, nuts, oats, rice, barley, chicken, pork, corn and beans; his mother, who was breast-feeding him, had to stop eating them all. At 10 months, doctors cut out 20 more foods, including all fruits and vegetables, and put Grayson on a hypoallergenic formula. Even so, his eczema was so bad that his parents put him in mittens, long-sleeved shirts and long pants so no skin was exposed. "Otherwise, he'd scratch himself until he would bleed," says his mother, Amy Grebe of Albuquerque, N.M.
For parents of children with food allergies, this may be both welcome and unsettling news: Many kids whose allergies were diagnosed on the basis of blood or skin tests alone may not be truly allergic to those foods, experts say.At wit's end, the Grebes took Grayson to National Jewish Health, a hospital in Denver that specializes in allergies and respiratory diseases. Doctors there suspected that his food allergies might not be causing the eczema—and that some might not be food allergies at all. After carefully supervised "food challenges"—giving him tiny amounts and monitoring him closely for signs of a reaction—a number of foods went back in his diet. "We came home with 12 foods he could eat," says Amy Grebe. "It's made so much difference in our lives."
Blood tests measure the level of antibodies, called immunogloblin E (IgE), a body makes to a particular food. But having IgE antibodies doesn't mean that a person will actually have an allergic symptom when they encounter it.
Skin-prick tests are slightly more predictive, but there, too, a red wheal in response to a skin prick doesn't necessarily mean that a child will have an actual allergic reaction to that food.
The only way to know for sure—short of encountering the food in real life—is with a food challenge test in a doctor's office or hospital. But those can be time consuming, expensive and nerve wracking, especially for parents who have seen a child encounter an anaphylactic shock, a life-threatening reaction in which multiple organs quickly shut down.
With use of allergy tests booming, more parents are coming away not fully understanding what they mean. That sometimes frustrates allergy experts. "When I first started doing this, my biggest job was convincing families to avoid a food. Now, the biggest job is to get families back on a food," says Hugh Sampson, a professor of pediatrics in the division of allergy and immunology at Mount Sinai School of Medicine in New York.
Several recent studies have underscored the gap between IgE antibodies and actual allergies. In this month's Journal of Allergy and Clinical Immunology, researchers in Manchester, England, reported that when 79 children who tested positive for peanut IgE antibodies were given food challenges, 66 of them could eat peanuts safely. At the American Association of Allergy, Asthma and Immunology (AAAI) conference last year, doctors from National Jewish reported that of 125 young patients given food challenges, more than half could tolerate foods they'd been told to avoid.
Read the whole thing at The Wall Street Journal.
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