Contradictory skin test and ImmunoCAP results–which is better?

This question comes up in my office almost everyday….should I do skin testing or blood work?  As you can see from the response of national experts, it depends.  There is NO test that can boast 100% accuracy to predict whether or not you will react to a food.  In fact, the gold standard if you will, is still the oral food challenge.  Here is some food for thought (really, do you have to pun)

  1. Clinical history is very important in determining food allergy.  If you can eat a food without difficulty breathing, rash, or hives, you are most likely not allergic.  You may have a positive test, but that only means you’ve had previous exposure to the food.
  2. I will often obtain both skin testing and ImmunoCap (blood work) to clarify the presence of IgE-mediated allergy. If both tests are negative, you may have an adverse reaction to a food, not the severe life-threatening anaphylaxis.  Very important distinction!
  3. If in doubt, a food challenge is always a procedure to consider.  Here’s why.
  4. Sometimes the food in question just isn’t worth the trouble to challenge.  No one says you have to eat strawberries!
  5. If you challenge peanuts for example, in the doctor’s office and experience anaphylaxis, better there than at home.  Epinephrine is more readily available and in many cases, IV access and full resuscitation is available within minutes of your reaction. 
  6. This is another reason why a single test or treating allergy without experience is not a good idea.  Read the link below and tell me just how complicated things can become!

Contradictory skin test and ImmunoCAP results.

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