A Mom writes:
I just got back results for my child’s ISAC test. If I am reading it correctly she is NOT allergic to sesame, cashew or hazelnut. She has multiple food allergies and any additions to her diet are a great help. What do I do now?
Ms. Tar Heel
Dear Ms. Tar Heel,
I certainly understand your excitement. For those who don’t know, ISAC (Immuno Solid-phase Allergen Chip) is shorthand for ThermoFisherScientific’s component test, offered under the brand ImmunoCap. Their website reads–
ImmunoCAP ISAC offers:
• Specific IgE measurement of allergen components from nearly 50 different allergen sources
• Semi-quantitative results for 112 allergen components
• Component resolved diagnostics using only purified natural or recombinant allergen components
Component testing is a big advance over older blood testing, which only measures IgE in the blood, and is not considered diagnostic of food allergy. Component testing shows sensitivity levels to different parts of food proteins that are more-or-less seriously allergenic. However, I must point out that every test is “just another test” and the real indicator is a food challenge. Mothers tell me that their kids remain reactive to certain things despite encouraging results like the ones you describe. So I instruct them in what I call the “skin-lip test” which they can do at home.
All they need is a sample of the food, a little water, and a camera. First they crush the food and mix it with water. They choose a patch of skin on the back (so that the child can’t inadvertently scratch it and get the allergen in their eyes or mouth) and draw a circle around it to make it easy to spot, then take a “before” picture. Finally they rub the allergen solution on it and wait 15 minutes, then take an “after” picture. If there is no reaction, they repeat the process—minus drawing the circle—on the patient’s lip. This time, if there is no reaction, they can ask their allergist to perform an office oral challenge.
Many parents are understandably cautious about doing the lip portion at home, so they might ask that their allergist do that part for them.
Dr. Paul Ehrlich