Nickan Research Institute Immunopathologia Persa 2423-8015 11 2 2025 07 01 Evaluation of fractional exhaled nitric oxide in patients with chronic cough based on causes e43744 e43744 10.34172/ipp.2025.43744 EN Amir Behnam Kharazmi https://orcid.org/0000-0003-1192-4893 Shima Abbasi https://orcid.org/0000-0002-7328-5647 Alireza Kashefizadeh https://orcid.org/0000-0001-7997-0365 Atefeh Abedini https://orcid.org/0000-0002-4262-9873 Sara Rashki Ghalenoo https://orcid.org/0000-0002-7638-2290 Journal Article 10.34172/ipp.2025.43744 2024 09 04 2024 11 02 Introduction: Cough is a common complaint in clinics, and diagnosing sub-acute or chronic cough is very important. Objectives: This study aimed to evaluate the association between fractional exhaled nitric oxide (FeNO) and causes of chronic cough and also, answer to this question that can we use FeNo for the diagnosis of the causes of chronic cough. Patients and Methods: In this descriptive-analytical cross-sectional study, 90 patients with a complaint of cough lasting more than three weeks were assessed. Spirometry and a methacholine stimulation test, complete blood count (CBC) serum IgE-diff, and FeNO were performed for all patients. Results: The mean age of the patients was 48.5±11.41 years, and 56.7% were male. Regarding medical history, 22.4% had asthma, 6.7% had chronic obstructive pulmonary disease (COPD), and 68.9% had no history of respiratory disease. Gastric reflux was detected in 42.2%. The mean duration of the onset of cough in the studied patients was 25.6±38.6 months. There was a significant correlation between the FeNO and IgE levels (P=0.048). The mean level of FeNO was 25±6.7 in patients with asthma, 57.3 ±18.7 in patients with COPD, and 22.8±1.6 in patients without a history of respiratory disease (P=0.002). Conclusion: This study’s findings showed a positive and significant correlation between FeNO and IgE. In addition, the FeNO level was significantly different based on the spirometry findings and respiratory diseases of asthma and COPD.