2025 – PAGE 100 – ALLERGY & IMMUNOLOGY
RADIOALLERGOSORBENT TESTING FOR IGE (AKA RAST)
Since radioallergosorbent testing (RAST) for IgE levels is IN VITRO (blood) testing, it is NOT affected by taking antihistamines.
FOOD ALLERGIES
When dealing with children with a strong family history of allergies, or who already have signs of atopy, it is suggested that parents introduce highly allergenic foods at home with oral antihistamines on hand and starting with only a single taste. ABDOMINAL PAIN may be the only sign of impending anaphylaxis.
INFANTS/TODDLERS: Allergies to eggs, milk, soy, or wheat are common. They will usually outgrow these by 5 years of age.
OLDER CHILDREN: Allergies to peanuts, shellfish, sesame, and tree nuts are common. They are less commonly outgrown.
PEARL: After an exposure, symptoms may continue to EVOLVE even up to two hours later. It is highly unlikely that the ONSET of an allergic response will start two hours after the food exposure.
PEARL: Do NOT restrict foods ONLY based on IgE results. Food allergies are clinical diagnoses. You must have the history (reaction) to support the diagnosis of a food allergy. Also, evidence does not support delaying the introduction of allergenic foods such as peanuts and shellfish. By avoiding the foods, a child can actually DEVELOP a true food allergy.
- AEROALLERGENS: If the child is maxing out with antihistamines, montelukast and nasal steroids, then refer to an allergist (even on the ABP exam).
PEARL: There is NO contraindication to giving contrast in kids with a shellfish allergy. Just give it. No need to pre-treat.
PEANUT ALLERGY
Early introduction, rather than avoidance, has been shown to be protective against developing a true peanut allergy. Although peanuts are legumes, for patients with a peanut allergy, you do not need to recommend against exposure to all legumes. Instead, caution against exposure to TREE NUTS since they are often processed in the same factories as peanuts, and because there is a 25%-50% likelihood that these patients ALSO have a tree nut allergy.
PEARL: “Peanut” is a misnomer because it is not a tree nut. Most tree nuts have the word NUT in them (e.g., hazelnut, macadamia nut). Legumes typically have the word BEAN in them (e.g., black bean, fava bean, lima bean). Don’t get confused on the pediatric boards.
PEARL: If the patient has severe eczema or egg allergies, then testing for a peanut allergy (skin testing or RAST) is recommended prior to the introduction of peanuts. If negative, peanuts may be introduced at home OR in a supervised office setting at 4-6 months of age based on preference. If positive, refer to a specialist. Based on the degree of positivity, either a graded oral food challenge will be done or the recommendation will be to avoid peanuts and treat the child as allergic.
PEARL: Children without eczema and children with mild-moderate eczema who do not have any food allergies do not need to be tested for peanut allergy and can try peanut products at 6 months of age in the home setting.
FOOD “SENSITIVITIES”
Foods like spicy foods and beans may be associated with abdominal discomfort ± flatus. These reactions should not be classified as allergies.