Phadia’s F14 test is used to detect blood levels of the IgE (antibodies) responsible for allergic reactions to soybeans. Soy is present in foods (milk, cheese, oil, sauces, etc.) in many forms, and often the word “soy” is not apparent in the product name (edamame, miso, “fauxmage” cheese, cooking sprays, etc.). The sometimes severe reactions are mainly seen in young children. The interpretation chart accompanying the result expresses the probability of an allergic reaction to soy, but not necessarily the severity of the reaction. Case history (symptoms, relation to meals, snacks, etc.) and clinical examination by the physician are essential for a reliable interpretation of the results.
A negative anti-soy IgE result (< 0.35 kU/L) indicates that soy is probably not responsible for the reported symptoms, but, especially in young children, it DOES NOT COMPLETELY RULE OUT THIS POSSIBILITY. All negative and positive results must be interpreted in light of the case history. There are no specific IgE levels that can be used to predict a severe reaction to soy. The double-blind oral food challenge remains the definitive technique for confirming a food allergy. Most children will get over their soy allergy within a few years. Tracking specific IgE levels over time can be useful in determining the age when soy can be reintroduced. In some cases, testing for IgE against specific soy components (Gly m4, Gly m5 and Gly m6) can help distinguish a real soy allergy from a cross allergy to birch pollen.