Asthma attack severity and urinary concentration of eosinophil X protein in children.

OBJECTIVE Determination of the urinary concentration of eosinophil protein X (U-EPX) may objectively predict the severity and activity of asthma in children. METHODS Concentrations of U-EPX in 80 non- atopic asthmatic children were compared with those in 25 healthy control children. The patients were studied during attacks and two weeks later. The severity of asthma attacks was determined according to a pre-existing score. U-EPX was measured by the specific radioimmunoassay technique (Pharmacia, Uppsala, Sweden). This measurement was correlated with the clinical and radiological investigations as well as with other variables such as blood oxygen saturation, peak expiratory rate and eosinophil count. RESULTS U-EPX concentrations were significantly higher in all asthmatic children during attacks (139.6 11.7 microg/mmol of creatinine) than those in the control group (35.3 6.2 microg/mmol of creatinine) (p < 0.001). Two weeks after resolution of the exacerbation, U-EPX significantly decreased (66.5 9.3 microg/mmol of creatinine) (p < 0.001). U-EPX concentrations were highest in patients with severe attacks (191.5 11.3 microg/mmol of creatinine) (p < 0.001). No statistically significant differences were found between mild (88.2 7.2 microg/mmol of creatinine) and moderate attacks (119.6 8.5 microg/mmol of creatinine). At the two-week follow-up, U-EPX concentrations in patients with mild or moderate attacks was similar to those in controls but were persistently elevated in the subgroup with severe attacks (103.8 9.4 microg/mmol of creatinine) (p < 0.001). No significant correlation was found between U-EPX concentrations and blood oxygen saturation, peak expiratory rate or eosinophil count. CONCLUSION A statistically significant correlation was found between U-EPX concentrations and the severity of attacks in asthmatic children. This substance could be useful in quantifying bronchial inflammation. This result could further be used as a marker of severity of disease exacerbation and would not only facilitate early diagnosis and staging of inflammatory and allergic disorders but would also allow therapy and interventions to be monitored.