Pulmonary Function Impairment

Asthma is a chronic inflammatory airway disease associated with variable airflow limitation and persistent respiratory symptoms. Vitamin D has been proposed as a potential biomarker related to immune regulation, asthma control, pulmonary function, and oxidative stress balance. This prospective cross-sectional observational study aims to investigate the association between serum 25-hydroxyvitamin D \[25(OH)D\] concentrations, asthma control, pulmonary function parameters, and erythrocyte oxidative stress biomarkers among Egyptian adults with bronchial asthma. A total of 200 adult asthma patients will be recruited from Abbassia Chest Hospital, Cairo, Egypt. Participants will undergo clinical assessment, Asthma Control Test (ACT), post-bronchodilator spirometry, serum vitamin D measurement, and oxidative stress biomarker assessment including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), and reduced glutathione (GSH). Participants will be categorized according to serum 25(OH)D concentrations into vitamin D deficient, insufficient, and sufficient groups. No intervention or treatment assignment will be performed. 5\. Detailed Description