Urinary leukotriene excretion profile in children with exercise-induced asthma compared with controls: a preliminary study

Background: Leukotrienes are among the most important mediators associated with inflammatory responses in patients with exercise induced asthma (EIA). The aim of this study was to investigate the impact of exercise on the urinary leukotriene profile. Hence, we compared post exercise changes of urinary leukotriene E4 (LTE4) concentration between children with EIA and healthy controls.

Methods: Ten children with EIA and 15 controls were enrolled. Both groups underwent a standardised exercise challenge test (ECT). LTE4 concentration was measured in urine samples obtained pre and post ECT, using enzyme immunoassay and adjusted by urinary creatinine concentrations.

Results: Median (minimum-maximum) pre ECT concentration of LTE4 was 17.82 (7.58-90.23 pg/ml) in EIA and 17.24 (4.64-64.02 pg/ml) in controls, p=0.86. LTE4 concentration post ECT were 23.37 (4.02-93.00 pg/ml) in EIA and 11.74 (0.13-25.09 pg/ml) in controls, p=0.02. Changes of LTE4 concentration post ECT were 2.54 (-31.98 to 43.31 pg/ml) in cases and -13.53 (-46.00 to 11.02 pg/ml) in controls, p=0.03. There was no significant correlation between basal predicted FEV(1) [%] and changes in LTE4 concentration in cases (i.e., r(s)=0.14) nor controls (i.e., r(s)=0.12). There was a tendency towards more pronounced changes in LTE4 concentration post ECT in children with moderate/mild persistent asthma compared to those with mild but intermittent asthma.

Conclusions: Children with EIA had significantly higher changes of urinary LTE4 concentrations post ECT compared to healthy controls. Urinary measurement of LTE4 may be an interesting and non-invasive option to assess control of EIA in children.