Skin prick testing and serum IgE measurement are limited in their ability to predict positive or negative responses to oral peanut challenge. We know that a percentage of patients who test positive for peanut in serum IgE or skin test, may not have clinical peanut allergy.
A few studies have examined the role of component-resolved diagnostics in the management of suspected peanut allergy. This test separates out the proteins and is able to measure the specific proteins that are likely to cause reactions. The serum test detects for the major peanut allergens, Ara h 1, Ara h 2, and Ara h 3 which are high risk for anaphylaxis. Ara h 8 is also a protein tested which is a low risk of systemic reaction and may show positive peanut sensitivity due to cross reactivity with pollens (ie. Birch).
A recent study demonstrated that Ara h 2 level >1.63 kU/L was 70% sensitive and 100% specific for positive peanut challenge. It was also related to the severity of symptoms in response to peanut challenge.
This test is available through our practice. It can be helpful to assess candidacy of patients for oral peanut challenge. If Ara h 1, 2 or 3 are negative, then the patient can pursue an oral food challenge. Conversely, if the test is positive, they are likely to fail an oral food challenge.
Component testing is also available for egg white and milk allergy.