Phadia’s F17 test is used to detect blood levels of the IgE (antibodies) responsible for the often severe allergic reactions to hazelnuts (filberts). The IgE detected with this test may be hazelnut-specific or involved in cross allergies to birch pollen, peaches and other related fruits. The interpretation chart accompanying the result expresses the probability of an allergic reaction to hazelnuts, but not necessarily the severity of the reaction. Case history (symptoms, relation to meals, snacks, birch pollen season, etc.) and clinical examination by the physician are essential for a reliable interpretation of the results.
A negative anti-hazelnut IgE result (< 0.35 kU/L) indicates that hazelnuts 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. Testing for IgE against specific allergens can, in some cases, help distinguish true allergies with a risk of severe reaction (anti Cor A8, anti Cor A9 or anti Cor A14 IgE) from cross allergies to birch (anti Cor A1 IgE). The double-blind oral food challenge remains the definitive technique for confirming the presence or absence of a food allergy.