Peanut Allergy: Diagnosis The diagnosis of peanut allergy is usually initiated when a parent reports a suspected episode or medical attention is sought for symptoms consistent with food allergies. The evaluation must include a careful history of the precipitating event being aware of possible hidden or contaminated sources of exposure. A careful list of signs and symptoms and their sequence and time from possible exposure is important. Allergic reactions to peanuts usually present within minutes in a child who was well until the time of exposure. Acute onset of wheezing without prior upper respiratory infections, exercise, or other known trigger should make the health professional suspicious of an acute allergic reaction. Prior history of asthma, atopic dermatitis, or family history of significant food allergies, especially peanut allergies, should also increase the health professional’s suspicion of peanut allergies. Skin-prick tests, radioallergosorbent (RAST) tests, and possible oral food challenges may be performed by an allergy specialist to confirm the diagnosis of peanut allergy and evaluate for other common food allergies (Sampson, 2002). Positive serum IgE antibodies do not always indicate clinical reactivity. The presence of peanut-specific serum IgE antibodies equal to or greater than 15 kU per liter is associated with a 95% or greater incidence of allergic reaction if a peanut is ingested. In children with serum IgE antibody levels below 15 kU per liter and an unclear history of peanut-induced symptoms, a physician supervised food challenge is necessary to make a definitive diagnosis (Sampson, 2002). Negative results for peanut-specific serum IgE, on the other hand, have a high negative predictive value, meaning if the serum IgE level is negative it is highly unlikely that the child has a peanut allergy or will exhibit clinical reactivity.