Urinary leukotriene E(4) in the assessment of nocturnal asthma

Background: Urinary leukotriene E(4) (LTE(4)) is a marker of the body's production of cysteinyl LTs, important mediators of airway inflammation. The role of the latter in nocturnal asthma is a topic of increasing interest. Objective: his investigation was aimed at determining whether nighttime attacks are associated with increased release of LTs, expressed by urinary LTE(4), and the relationship between the two phenomena. Methods: Three groups were studied group A, seven control subjects: group B, nine asthmatic patients without nocturnal attacks; and group C, nine asthmatic patients with a comparable daytime FEV(1) but who were experiencing nocturnal exacerbations (morning dips in peak expiratory flow > 20%). Urine was collected over 24 hours in three samples (9:00 AM to 3:00 PM; 3:00 PM to 9:00 PM; and 9:00 PM to 9:00 AM). LTE(4) was measured by high-performance liquid chromatography and radioimmunoassay and expressed as nanograms per millimole of creatinine. Results: No significant difference between urinary LTE(4) were noticed groups A and B. Conversely, in group C urinary LTE4 at night (geometric mean with 95% confidence interval: 35.16 with 28.77-42.85) was significantly higher than that of the other samples (respectively 23.12 with 17.78-30.06, p < 0.05; and 25.18 with 21.03-30-13, p < 0.02); it was also significantly higher than in all samples of other groups. A significant (p < 0.02) linear correlation was observed between morning dip in peak expiratory flow and the log urinary LTE4 in the nocturnal sample. Conclusion: These results indicate the role of LTs in nocturnal asthma and suggest that urinary LTE4 may be a useful marker of this condition.