Phadia’s F207 test is used to detect blood levels of the IgE (antibodies) responsible for allergic reactions to clams. Although some people may be allergic only to clams, cross allergies can be expected with oysters and other molluscs (blue mussels, scallops, squid, etc.). Many people are also allergic to shellfish (shrimp, lobster, crayfish, etc.), and multiple seafood allergies are common. The interpretation chart accompanying the result expresses the probability of an allergic reaction to clams, but not necessarily the severity of the reaction. Case history (symptoms, relation to meals, etc.) and clinical examination by the physician are essential for a reliable interpretation of the results.
A negative anti-clam IgE result (< 0.35 kU/L) indicates that clams 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. In more complex cases, the double-blind oral food challenge under medical supervision remains the definitive technique for confirming the presence or absence of an allergy to clams. Unlike milk and egg white allergies, which many children outgrow, the hypersensitivity to clams and other seafood tends to develop in adulthood and persist for life.