Phadia’s F37 test is used to detect blood levels of the IgE (antibodies) responsible for allergic reactions to blue mussels. Although some people may be allergic only to mussels, cross allergies can be expected with oysters and other molluscs (clams, scallops, squid, etc.). Many people are also allergic to crustaceans (shrimp, lobster, crayfish, etc.), and multiple seafood allergies are common. The interpretation chart accompanying the result expresses the probability of an allergic reaction to blue mussels (and possibly other molluscs), 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 blue mussel IgE result (< 0.35 kU/L) indicates that blue mussels are probably not responsible for the symptoms reported by the individual, 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 mussels. Unlike milk and egg white allergies, which many children outgrow, the hypersensitivity to mussels and other seafood tends to develop in adulthood and persist for life.