R.W. Dal Negro 1 , M. Visconti 1 , C. Micheletto 1 , S. Tognella 1 , M. Guerriero 2 1 Lung Dept., Orlandi Gen. Hospital., Bussolengo - Verona, Italy - E-mail: rdalnegro@ulss22.ven.it 2 ESI Dept., Statistical Section, University of Verona, Italy Reference urinary LTE 4 levels in normal individuals: a pilot study Summary The definition of reference normal values for urinary LTE4 still represents an open question. Aim: to assess the influence of gender and age on urinary LTE4 levels in nor- mal individuals. Methods: after their informed consent, urinary LTE4 was measured in 124 well matched, non smoker, non atopic subjects (mean age 49.5 y±20.1 sd; range 4-85 y, 57 m;) without any clinically evident disease and not taking any drug for sev- eral months. In all subjects, urine were collected in the morning, and processed by an immunoenzimatic method (Cayman Chem, Mi, USA) via the Triturus system (Gri- fols, Spain). Statistics: t test, anova, linear regression, assuming p<0.05. Results: mean urinary LTE4 were 57.3 pg/ml in males (mean age 51.2 y±21.3 sd) and 57.0pg/ml in females (mean age 48.1 y±19.1 sd), p=ns. Linear regression showed no relationship between urinary LTE4 levels and subjects’ age in the whole sample of sub- jects. When subjects were divided according to 4 different classes of age (0-14; 15-40; 41-60; >60), anova proved that mean urinary LTE4 levels were significantly differ- ent in the different classes of age, being higher in younger subjects (67.1 pg/ml ±33.4 sd; 69.8 pg/ml ±27.5 sd; 57.1 pg/ml ±25.4sd, and 45.1 pg/ml ±24.9, respectively) (anova p<.002; Welch test p<.005). Conclusions: 1) gender does not affect urinary LTE4 lev- els in normals; 2) mean urinary LTE4 concentrations tend to a slight, but significant, decrease with the increase of the subjects’ age, and this is clear in those over-60; 3) refer- ence values for younger and older normal subjects (such as, under- and over-60 years) should be assumed accordingly. Key words Urine LTE4, reference values, normal individuals Corresponding author Roberto W. Dal Negro Lung Dept., Orlandi Gen. Hospital Via Ospedale, 2 I-37012 Bussolengo, Verona, Italy Tel: +39 045 6712193 Fax: +39 045 67122544 E-mail: rdalnegro@ulss22.ven.it Introduction Leukotrienes (LTs) have an established role in a wide vari- ety of inflammatory diseases, including asthma, allergic rhinitis, atherosclerotic cardiovascular disease, inflammato- ry bowel disease, multiple sclerosis and cancer (1). LTs are metabolites of arachidonic acid and their synthesis can be triggered by a variety of soluble and particulate stimuli, in- cluding antigens, microbes, cytokines, immune complexes and model agonists such as calcium ionophores. Leukotriene C4 (LTC4), the intracellular parent of the cys- teinyl leukotrienes (cysLTs), is formed by conjugation of LTA4 and reduced glutathione by LTC4 synthase in mast cell, eosinophils, basophils, and macrophages (2). Of the 3 cysLTs,only LTE4 is stable enough to be detectable in ex- tracellular fluids (3). Eur Ann Allergy Clin Immunol VOL 43, N 1, 22-28, 2011 ORIGINAL ARTICLE