[Measurement of plasma histamine, urinary N-methylhistamine and peripheral eosinophil counts in food provocation tests in infants and children with atopic dermatitis].

N-methylhistamine (NMH) of the urine histamine metabolite, plasma histamine and eosinophil counts in the blood were determined in fourteen atopic children (aged 5 months-6 years, Mean = 2.8 years, M:F = 7:7) with food hypersensitivities. Urinary NMH levels during six hours in positive provocation tests were much higher than in those of negative provocation tests (534 +/- 331 micrograms/g Cr in positive tests versus 343 +/- 58 micrograms/g Cr in negative [p < 0.005]). Eosinophil counts during three hours in positive provocation tests were much lower than they were before the tests (530 +/- 239/microliters versus 248 +/- 142/microliters [p < 0.001]). However plasma histamine levels were elevated in only three of seven patients in positive food provocation tests. In addition, the percent changes in NMH levels and eosinophil counts in positive provocation tests were much higher than in those of negative provocation tests (p < 0.02, p < 0.001). Therefore it is suggested that changes in urinary NMH levels and eosinophil counts in the blood are good parameters for diagnosing food hypersensitivity in children.