the Role of Fractional Exhaled Nitric Oxide (FeNO) and Inflammatory Biomarkers in Diagnosing Non-chronic Cough in Pediatric Patients: A Cross-sectional Study.

Fractional exhaled nitric oxide (FeNO) has emerged as a potential biomarker for differentiating between various causes of non-chronic cough, particularly in conditions associated with airway inflammation, such as asthma. This study aimed to evaluate the diagnostic efficacy of FeNO in pediatric patients with non-chronic cough and its ability to differentiate between asthma exacerbations and respiratory tract infections. Seventy-five pediatric patients aged 10-18 years with non-chronic cough were categorized into three groups: good control asthma (GCA, n=28), acute asthma exacerbation (AAE, n=26), and respiratory tract infection (RTI, n=21). Clinical assessments included FeNO measurement, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell (WBC) count, hemoglobin (HB), platelet count (PLT), and immunoglobulin E (IgE) levels. Univariate and multivariate multinomial logistic regression models were applied to assess the predictive value of these variables. FeNO levels were significantly higher in the AAE group (46.58±22.66 ppb) compared to the GCA and RTI groups, indicating elevated eosinophilic airway inflammation in asthma exacerbations. CRP was a significant predictor of both AAE and RTI, with a one-unit increase in CRP increasing the odds of exacerbation or infection by 2.6-fold. Body max index (BMI) was inversely associated with the risk of RTI. Hemoglobin, platelet count, and IgE levels were significantly higher in the AAE group compared to the other groups, while WBC counts, though elevated, were not statistically significant. FeNO associated with other inflammatory markers, including CRP and BMI, could enhance diagnostic accuracy and inform clinical decision-making in managing pediatric respiratory conditions. To confirm these results, future studies with larger sample sizes should be performed.