New Tests for Food Allergies

It is estimated that about 3 million children and adolescents in the U.S. have food allergies. As an allergy doctor serving Mclean VA, I see many food allergy cases. For reasons that are not entirely clear, the incidence (newly reported and diagnosed cases) has been increasing steadily over the past several years.

Milk, wheat, egg, peanuts, tree nuts, and shellfish account for a vast majority of food allergies. Among these, peanuts and tree nuts (e.g., almonds, Brazil nuts, cashews, hazelnuts, pecans, walnuts) are more likely to cause serious life threatening allergic reactions.  They are also less likely to be “outgrown” than other food allergies.

The diagnosis of peanut and tree nut allergies from an allergy doctor in Mclean VA is based on a detailed history of the nature of reaction and the specific food trigger along with the results of prick skin tests and/or blood tests to estimate the level of an antibody called a specific IgE.  An elevated specific IgE level indicates a higher likelihood of a reaction upon exposure to the specific food.  Elimination of any exposure to the involved food and carrying a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q) are the only treatment options at this time.

Many children diagnosed with peanut and tree nut allergies and their parents experience considerable anxiety about accidental ingestion and the potential for a serious reaction.  A few newly available tests may ease their fears to some extent.

Both prick skin tests and blood tests, while extremely useful in detecting sensitivity, can also be falsely positive in a significant percentage of patients (especially in children with eczema) and can overestimate the risk of a reaction upon exposure.  Peanuts and tree nuts contain more than 10 types of proteins which trigger an allergic reaction, and some of them are more dangerous than others.

Until recently, the available tests for peanut allergy only measure the total quantities of all peanut specific antibodies.  A new “component” blood test can measure the levels of individual peanut protein antibodies, helping us better delineate the actual risk of a reaction.  The five major peanut proteins are as follows:  Ara h 1, Ara h 2, Ara h 3, Ara h 8, and Ara h 9.  An elevated Ara h 1, Ara h 2, or Ara h 3 level predicts a higher likelihood of a reaction than an elevated Ara h 8 or Ara h 9 protein level.

Children with elevated Ara h 2 levels should strictly avoid all exposure to all peanut products at all times.  Ara h 8 resembles the protein found in birch pollen, which is one of the tree pollens that is responsible for hay fever (i.e., allergic rhinitis) in the Spring in the Washington, DC metropolitan area.  Higher levels of Ara h 8 in the absence of Ara h 1, Ara h 2, and/or Ara h 3 can predict less severe reactions with symptoms limited to an itchy mouth, throat, and/or lips [i.e., Pollen-food syndrome (formally known as oral allergy syndrome)].  These children can undergo oral food challenges to peanuts under controlled conditions in the presence of a board certified allergist.

Oral food challenges to peanuts involve consumption of tiny quantities of peanut-containing foods while closely monitoring for adverse reactions.  Small incremental doses are given at regular intervals.  If the usual daily dose is tolerated, peanut can then be integrated in the regular diet of the patient.  It goes a long way in reassuring the family and alleviating the anxiety.  Similar tests are also available for certain tree nut specific component proteins.

The board certified allergists at Black & Kletz Allergy treats both adults and children and will gladly answer any questions you have concerning food component testing and related food allergy issues.  Black & Kletz Allergy has 3 offices in the Washington, DC, northern Virginia, and Maryland metropolitan area with locations in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA.  We offer on-site parking at each location and the Washington, DC and McLean offices are also Metro accessible.  There is a free shuttle that runs between our McLean office and the Spring Hill metro station on the silver line.  If you would like to make an appointment with an allergy doctor Mclean VA, please call us or alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day.  Black & Kletz Allergy has been providing quality allergy, asthma, sinus, and immunological services to the DC metro area for more than 50 years.