Vitamin D Status and Asthma Control, Pulmonary Function, and Oxidative Stress in Adults With Bronchial Asthma

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

Inclusion Criteria * Age ≥ 18 years. * Confirmed diagnosis of bronchial asthma. * Clinically stable at the time of assessment. * Availability of spirometry results. * Availability of laboratory investigations including serum 25(OH)D and oxidative stress biomarkers. Exclusion Criteria * Other chronic pulmonary diseases. * Active respiratory infection. * Malignancy. * Significant renal or hepatic disease. * Pregnancy. * Current vitamin D supplementation. * Other conditions known to markedly influence oxidative stress status.