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 inflammat ion. The role of the latter in nocturnal asthma is a topic of increasi ng interest. Objective: his investigation was aimed at determining whe ther nighttime attacks are associated with increased release of LTs, e xpressed by urinary LTE(4), and the relationship between the two pheno mena. Methods: Three groups were studied group A, seven control subjec ts: group B, nine asthmatic patients without nocturnal attacks; and gr oup C, nine asthmatic patients with a comparable daytime FEV(1) but wh o were experiencing nocturnal exacerbations (morning dips in peak expi ratory 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 radioim munoassay and expressed as nanograms per millimole of creatinine. Resu lts: No significant difference between urinary LTE(4) were noticed gro ups A and B. Conversely, in group C urinary LTE4 at night (geometric m ean with 95% confidence interval: 35.16 with 28.77-42.85) was signific antly higher than that of the other samples (respectively 23.12 with 1 7.78-30.06, p < 0.05; and 25.18 with 21.03-30-13, p < 0.02); it was al so significantly higher than in all samples of other groups. A signifi cant (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 asth ma and suggest that urinary LTE4 may be a useful marker of this condit ion.