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Nine percent of children may outgrow their tree nut allergies

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09.11.2005

From the Journal of Allergy & Clinical Immunology

Approximately 9% of children with an allergy to tree nuts will outgrow their allergy, including children who have previously experienced a severe allergic reaction, according to a study in the November 2005 Journal of Allergy & Clinical Immunology (JACI). The JACI is the peer-reviewed, scientific journal of the American Academy of Allergy, Asthma & Immunology (AAAAI).

Up to this point, researchers thought that allergies to tree nuts, which include cashews, almonds, walnuts, hazelnuts, macadamia nuts, pecans pistachios, and pine nuts, lasted a life time. It is estimated that 1%-2% of the United States population is allergic to peanuts, tree nuts or both. Previous research has shown that children allergic to peanuts have a 20% chance of outgrowing their allergy.

A research team led by Robert A. Wood from Johns Hopkins University School of Medicine, evaluated 278 children (Ages 3-21 years) to determine the percentage of those who will outgrow their allergy. Researchers also sought to determine what level of tree nut specific-IgE in the blood would be a safe level before testing the child through an oral food challenge, which is currently the best way to prove that a child has outgrown their food allergy.

The study found:

• Approximately 9% of children allergic to tree nuts outgrow their allergy, including children who have had a previous severe allergic reaction.
• Children who are allergic to multiple types of tree nuts are unlikely to outgrow their allergy.
• 58% of children with tree nut specific IgE levels of less than 5 kilounits per liter passed an oral challenge.

Based on these findings, researchers recommend that children with a current tree nut allergy be re-evaluated periodically by their allergist/immunologist to assess whether they have developed a tolerance and whether an oral challenge should be given.
While an ideal cut-off has not been established, researchers suggest that oral challenges should be considered in children four years and older, and who have less than five kilounits per liter of tree-nut specific IgE in their blood.

Since tree nut allergies were previously thought to last a lifetime, few patients underwent a re-evaluation to determine if their allergy still existed. They were simply told to avoid tree nuts, and were prescribed epinephrine to take in the event a severe reaction occurred. However, based on the results of the current study, it is now clear that periodic reevaluation is warranted. While only 9% will outgrow their allergy, researchers stress that it is important that these patients be identified so that they no longer need to worry about this otherwise potentially deadly allergy.

John Gardner | Source: EurekAlert!
Further information: www.aaaai.org

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