EVALUATION OF FX5 RAST IN THE DIAGNOSIS OF FOOD ALLERGY IN THE ADULT AND CHILD

Because of the usual difficulties encountered in the diagnosis of food allergy other than in clinically typical situations, the value of Fx5 as a screening test was sought in 105 selected patients then 95 consecutive patients. The theoretical value of the test was also sought in 500 food allergy sufferers, 60 children and 440 patients. Fx5 identified the presence in plasma of one or more of the following food allergens: peanuts, wheat, egg white, cows milk proteins, fish and soybean. Fx5 was positive in 75 per cent of cases in the presence of monosensitization to one of these allergens, in 80 per cent of cases in the presence of bisensitization and in 100 per cent of cases in the presence of sensitization to a minimum of 3 of the allergens tested simultaneously. The test was more sensitive in the child (75 per cent) than in the adult (50 per cent). It was also more sensitive in atopic dermatitis than in other manifestations of food allergy. These differences were linked to the larger number of types of sensitization seen in the child and the nature of those sensitizations most common in atopic dermatitis. This test deserves, even for reasons of economy, a primary role in the diagnosis of food sensitizations.