Phadia’s F203 test is used to detect blood levels of the IgE (antibodies) responsible for allergic reactions to pistachios. The IgE detected in the test can be pistachio-specific or involved in cross allergies with cashews and mangoes and sometimes other nuts (walnuts, Brazil nuts, hazelnuts, etc.). The interpretation chart accompanying the result expresses the probability of an allergic reaction to pistachios, 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-pistachio IgE result (< 0.35 kU/L) indicates that pistachios are probably not responsible for the symptoms reported by the person, but it DOES NOT COMPLETELY RULE OUT THIS POSSIBILITY. All negative and positive results must be interpreted in light of the case history. The double-blind oral food challenge remains the definitive technique for confirming the presence or absence of a food allergy. In most cases, allergies to pistachios and other nuts are persistent, but it has been shown that some people may get over them.