Phadia’s F18 test is used to detect blood levels of the IgE (antibodies) responsible for moderate to severe allergic reactions to Brazil nuts. The IgE detected in the test may be specific to Brazil nuts or involved in multiple allergies with other nuts (walnuts, pecans, hazelnuts, almonds, etc.) and sometimes peanuts. The interpretation chart accompanying the result expresses the probability of an allergic reaction to Brazil nuts, 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-Brazil nut IgE result (< 0.35 kU/L) indicates that Brazil nuts are probably not responsible for the symptoms reported by the person, but it DOES NOT COMPLETELY RULE OUT THIS POSSIBILITY. Both negative and positive results must be interpreted in light of the case history. The double-blind oral food challenge, under strict medical supervision, remains the definitive technique for confirming the presence or absence of a food allergy. In most cases, allergies to Brazil nuts and other nuts are persistent, but it has been shown that some people may get over them.