Background: Vitamin D has a potential to modulate inflammatory response against noxious particles in patients with chronic obstructive pulmonary disease (COPD). The present study was conducted to determine the status of serum vitamin D in COPD versus healthy group.

 Methods: The patients presented to the outpatient pulmonary clinic of Ayatollah Rouhani Hospital, Babol Iran. Diagnosis of COPD was confirmed based on airflow limitation defined as FEV1/FVC ratio <70% and FEV1< 80% of predicted. All eligible patients aged ≥ 40 years old entered the study. Pulmonary infection, tuberculosis, pleural effusion, congestive heart failure, pulmonary hypertension and embolism, restrictive airway disease, conditions leading changes in vitamin D metabolism and absorption were excluded. Serum 25-hydroxyvitamin D (25-OHD) was determined by electrocheminluminescence method and levels <20, 20-29, and ≥30ng/ml were considered as deficiency, insufficiency, and sufficiency. In statistical analysis, the frequency of serum 25-OHD deficiency and insufficiency in patients were compared regarding age of ≤ 50 or >50 years old. All patients were males and age and sex-matched controls were selected among healthy subjects accompanied COPD patients.

 Results: Ninety patients and 100 controls with respective mean (±SD) age of 64.8±11.7 and 62.6±11.7 years old (P=0.19) were studied. Compared with control, proportions of serum 25-OHD deficiency and insufficiency in patients >50 years were higher and deficiency was lower (61.5% vs 87.5%, P=0.11).

 Conclusion: These findings indicate that a significant proportion of young COPD patients have insufficient serum 25-OHD. Regarding a positive relationship between 25-OHD and FEV1 in COPD, these findings highlight serum 25-OHD assessment in COPD for recognizing high risk patients.