Title: Does Serum Leptin Differ Between Patients With Rhinitis Of Allergic Vs Nonallergic Aetiology?
Abstract: Leptin, is a 16-kD-adipocyte-derived-cytokine that may play a critical role in airway inflammation. Leptin has rarely been evaluated in allergic rhinitis (AR), but not in rhinitis of different aetiology. We aimed to compare serum leptin levels between AR and nonallergic rhinitis (NAR), as well as contributing factors. Patients were enrolled based on chronic nasal symptoms. Serum leptin levels (ng/mL) were analyzed with a solid-phase-enzyme-amplified-sensitivity-immunoassay (DIAsource Immunoassays S.A. Louvain-la-Neuve, Belgium). Total nasal symptom scores (TNSS), and body mass index (BMI, kg/m2) were evaluated. A total of 322 patients (64.6% F) with a mean age of 29.47±11.59yr, were recruited and grouped as AR (n:221) and NAR (n:101). Leptin levels were insignificantly higher in patients with NAR (5.68 ±0.99ng/ml) than AR (4.22±0.39ng/ml), as well as BMI. Although leptin was significantly higher in females in both groups, its higher level in patients with BMI≥25kg/m2, compared to patients with BMI<25kg/m2, was significant only in AR (6.62±1.1ng/ml, 3.56 ±0.45ng/ml, p=0.004). Likewise, leptin was significantly correlated with age, BMI, and eye symptoms (r=0.154, r=0.165, r=-0.167), in allergic rhinitics. Despite higher TNSS in AR, compared to NAR, neither severity/seasonality of symptoms, nor sensitization type were related with leptin levels. This preliminary study provides the first evidence of similar serum leptin levels in patients with allergic and nonallergic rhinitis. Serum leptin levels were higher in female gender and obese rhinitics, with a positive correlation with BMI in AR. These results suggest that leptin measurement have limited value as the sole diagnostic tool when differentiating AR and NAR.