Urinary LTE4 Levels as a Diagnostic Marker for IgE-Mediated Asthma in Preschool Children: A Birth Cohort Study

OBJECTIVES Leukotrienes play a central pathophysiological role in allergic asthma. The aim of this study was to investigate the utility of measuring urinary leukotriene E4 (LTE4) levels in the diagnosis of atopic diseases in early childhood. METHODS Children aged 0 through 4 years from a birth cohort in the Prediction of Allergies in Taiwanese Children (PATCH) study were enrolled. Urinary LTE4 levels were measured and its association between total serum IgE levels, allergen-specific IgE sensitization and atopic diseases were assessed. RESULTS A total of 182 children were regular followed up at clinics for a four-year follow-up period. Urinary LTE4 levels appeared to be elevated in children with total serum IgE levels exceeding 100 kU/L, allergen-specific IgE sensitization after 2 years of age. Elevation of urinary LTE4 levels (≥500 pg/mg of creatinine) significantly discriminated high serum total IgE levels (≥100 kU/L) at age 2 (P = 0.027). A higher level of total serum IgE or urinary LTE4 was significantly associated with the risk of developing allergic rhinitis and asthma at age 3. A significantly higher urinary LTE4 level was found in children with a combination of IgE sensitization and asthma at age 4. CONCLUSIONS Urinary LTE4 levels appear to be highly associated with IgE sensitization and its related allergic airway diseases after age 2. The measurement of urinary LTE4 (≥500 pg/mg of creatinine) could not only be a non-invasive method for atopic predisposition but also potentially provide a strategy for the diagnosis and management of asthma in preschool children.