Aspirin-induced asthma (AIA) is a syndrome characterized by intolerance to aspirin (ASA), nasal polyps and bronchial asthma, the metabolic shift of arachidonic acid towards the lipoxygenase pathway and hyper-production of cysteinyl-leukotrienes (cys-LTs) being the current pathogenetic hypothesis. The research for both sensitive indicators and safe diagnostic tests is still attracting. Aim of the study was to measure changes in urinary LTE₄ excretion and in nasal function (Resistance—Req, and Volume—Vol, assessed by acoustic rhinomanometry (AR)) following a nasal provocation test (NPT) with ASA:LTE₄ measurements have been never previously used to our knowledge for assessing nasal responsiveness to ASA.

After written consent, 118 mild-to-moderate asthmatics (48 males, mean age 41.8 years±11.9sd, range 25–70 years; basal FEV₁=80.1%pred.±5.8sd) underwent NPT by nasal instillation of ASA (total maximal dose 25mg). Spirometry, acoustic rhinomanometry (AR; TM Hood Lab., USA) and urinary LTE₄ (pg/mg creatinine; Cayman Chemical, MI, USA) were measured in baseline and 2h after the ASA challenge.

t-Test between means±sd, assuming  , and linear regression between all variables considered.

In 67 ASA-intolerant asthmatics, FEV₁ did not change significantly following NPT (81.7% pred.±5.1sd in baseline, 80.5% pred.±4.1 after NPT, P=ns) even in the presence of a significant decrease of Vol (11.3cm³±4.1sd in baseline, 5.9cm³±4.2sd after NPT,  ), a substantial increase of Req (0.88cmH₂O/l/min±0.11sd in baseline, 2.41cmH₂O/l/min±0.77 after NPT,  ), and urinary LTE₄ excretion (433.0pg/mg±361.7 in bsln, 858.0pg/mg±471.6 90min after NPT with L-SA,  ). NPT did not affect FEV₁ also in 51 ASA-tolerant asthmatics (89.7% pred.±6.9 in bsln, 86.6% pred.±4.3 after NPT), but in these subjects also Vol (from 14.9cm³±4.2sd to 14.6cm³±3.8sd), Req (0.38cmH₂O/l/min±0.14 in bsln, 0.26cmH₂O/l/min±0.2 after NPT, P=ns), and urinary LTE₄ (333.1pg/mg±202.8 in bsln, 318.0pg/mg±198.7 after NPT, P=ns) remained unchanged. Only pre-NPT LTE₄ values proved related to pre-NPT Req and Vol values (  and  , respectively), but not to patients’ age ( ), and basal FEV₁ ( ).

In ASA-intolerant patients, NPT with lysine-aspirin (L-ASA) only induces a substantial nasal obstruction and enhances urinary LTE₄ excretion in the absence of any significant bronchial obstruction. Nasal ASA challenge proves a test absolutely safe for asthma patients suspected of ASA intolerance. Measures of urinary LTE₄ excretion contributed significantly to magnify the discriminant and the diagnostic value of NPT.