Relationship between serum vitamin D and forced expiratory volume in patients with chronic obstructive pulmonary disease (COPD)

Vitamin D deficiency seems to be associated with pulmonary function deterioration. The present study was designed to investigate the relationship between serum vitamin D and forced expiratory volume in patients with chronic obstructive pulmonary disease (COPD). From September 2011 to April 2012 eighty consecutive patients with COPD presented to an outpatient clinic of Babol University- Teaching Hospital entered to the study. Diagnosis of COPD was confirmed according to clinical findings and pulmonary function test. Serum 25-hydroxyvitamin D (25-OHD) was assessed by chemiluminuscence method and postbronchodilator forced expiratory volume in 1s (FEV1) was measured in all patients. The objective of this study was to determine the relationship between serum 25-OHD concentrations and FEV1 value. The patients were classified according to serum 25- OHD concentrations as less 10ng/ml, 10-19.9; 20-29.9; 30-39.9; and 40ng/ml or higher. The mean values of FEV1 for each class of serum 25-OHD were determined and compared. The mean age of patients was 67.4±11.5 years. The mean FEV1 volume in serum 25-OHD deficient COPD was lower than sufficient COPD (1.550±0.55 vs 1.650±-0.58, p=0.45). Mean FEV1 values increased from 1.55±0.55 L in patients with mean serum 25-OHD <20 ng/ml to 1.94±0.74 L in COPD patients with mean serum 25-OHD ±>40 ng/ml. There was a dose-response pattern of relationship between FEV1 and serum 25-OHD. However, the relationship did not reach to a statistically significant level. These findings indicated a relationship between serum 25-OHD concentration and FEV1 volume in patients with COPD and suggest optimization of serum vitamin D levels in COPD.